1. Preliminaries
This section gathers the numerical uncertainty models used in the paper. Unless stated otherwise, functions are defined on the real line .
1.1. Fuzzy Number and Neutrosophic Number
A fuzzy number represents an imprecise real quantity using a membership function
that is normal, convex, upper semicontinuous, and has compact support [
1]. Related concepts also include the
intuitionistic fuzzy number [
2,
3] and the
picture fuzzy number [
4,
5], both of which have been extensively investigated as important extensions of fuzzy numerical representations. A neutrosophic number extends this concept by assigning to each
three degrees: truth
, indeterminacy
, and falsity
[
6,
7]. Related concepts include the
trapezoidal neutrosophic number [
8,
9,
10,
11] and the
triangular neutrosophic number [
12,
13,
14,
15], which are widely studied in the literature.
Definition 1 (Fuzzy Number).
[1] A fuzzy number
is a fuzzy set A on with membership satisfying:
- (i)
Normality: .
- (ii)
Convexity: for all and ,
- (iii)
Upper semi-continuity: is u.s.c. on .
- (iv)
Compact support: is compact.
Definition 2 (Single-Valued Neutrosophic Number on
).
[6,7] A single-valued neutrosophic number (SVNN)
on is a triple with . For each , , , and denote, respectively, the degrees of truth, indeterminacy, and falsity, with A neutrosophic number
is normal
if and , convex
if each α-cut of T is convex while the β-superlevel of F is convex (dually), and well-posed
if are u.s.c. and have compact supports (whenever appropriate).
Example 1 (Canonical triangular instances).
A triangular fuzzy number with mode m and spreads is
A triangular SVNN can be specified by where T is triangular as above, I is a (possibly wider) triangular cap centered at m, and F is the pointwise reflection (or a wider trapezoid), yielding a compact, u.s.c. triple.
1.2. Plithogenic Number
Plithogenic theory augments membership with explicit
attributes and a
contradiction degree between attribute values, guiding aggregation and reasoning [
16,
17].
Definition 3 (Plithogenic Number).
[16] Fix an attribute v with value domain V and a symmetric contradiction map with . A plithogenic number
on is a family of membership functions together with an aggregation operator (t-norm/t-conorm–based) that depends on c:
It is normal/convex/u.s.c./compactly supported when inherits these properties from under .
Example 2 (Two-attribute aggregation).
Let , with triangular on . Suppose and define where ⊕ is a t-conorm (e.g., max). Then is a normal, convex, u.s.c. membership on whenever the constituents are, yielding a well-posed plithogenic number.
1.3. Rough Number
A rough number is an interval of lower and upper mean attribute values over rough approximations under an equivalence relation [
18,
19,
20]. Extensions of the rough number, such as the Fuzzy Rough Number and Neutrosophic Rough Number, have also been studied [
21,
22,
23,
24,
25,
26].
Definition 4 (Universe and Equivalence Classes).
(cf.[18]) Let U be a nonempty finite set (the universe
). Let be an equivalence relation on U. For each , denote its equivalence class by
Definition 5 (Lower and Upper Approximations).
(cf.[18]) For any , define its lower approximation
and upper approximation
with respect to R by
Here collects all elements that definitely belong to G, while collects those that possibly belong.
Definition 6 (Rough Number).
(cf.[18,27,28]) Let be an ordered partition of U with . For each class , define:
Then the rough number
of is the interval
Example 3 (Rough Number — Affordable houses by neighborhood (fully worked)).
Universe and equivalence. Let be eight houses. Neighborhood (indiscernibility) classes are
Let the numeric attribute be the listing price (in $1000):
Target set (“affordable”). Define
Lower/upper approximations w.r.t. neighborhood classes:
Rough number (mean prices). Using we compute
Hence the rough number
of “affordable” is
Based on neighborhood indistinguishability, the definitely-affordable mean price is $387.5k (from only), while the possibly-affordable mean rises to $389.0k when including mixed neighborhoods () that contain both affordable and non-affordable houses.
1.4. Ordered Fuzzy Number
An ordered fuzzy number represents uncertainty by two continuous boundary functions over [0,1], producing increasing and decreasing membership curves [
29,
30].
Definition 7 (Ordered Fuzzy Number).
[31,32,33,34] An ordered fuzzy number
(also called an ordered fuzzy real
) is an ordered pair where the functions are continuous. The corresponding membership curves are
Example 4 (Ordered Fuzzy Number: commute time).
A commuter says the “most typical” door-to-door time is minutes, rarely below 30 or above 60. As an ordered fuzzy number with triangular α-cuts, take so the α-cut is .
1.5. Ranking Fuzzy Number
A ranking fuzzy number is a fuzzy numerical entity whose order is determined by a ranking function or relation that induces a total preorder among fuzzy numbers, typically through scoring integrals or possibility measures [
35,
36,
37,
38,
39]. This ordering is consistent with the natural order on real numbers, ensuring that when the fuzzy numbers degenerate to crisp values, their ranking coincides with the classical numerical comparison.
Definition 8 (Ranking of fuzzy numbers). Let be a class of fuzzy numbers on (normalized, convex, u.s.c.). A ranking is either
- (i)
a map inducing a total preorder , or
- lbbel=()
a complete, transitive binary relation ⪯ on itself.
It is order-consistent
if for crisp (seen as degenerate fuzzy numbers ) we have . Typical realizations compute R by integrating the possibility distributions against a user viewpoint
(satisfaction-function approach), or by possibility/necessity measures in possibility theory.1
Example 5 (Ranking Fuzzy Number: choosing a laptop).
A buyer scores two laptops by overall satisfaction (in points) as triangular fuzzy numbers:
Using the centroid ranking ,
so .
1.6. Grey Number
A grey number denotes an unknown real value constrained between known bounds, represented as interval
, modeling incomplete information (cf.[
40,
41,
42,
43,
44,
45]).
Definition 9 (Grey Number).
[46,47] A grey number is a real quantity constrained by known lower and upper bounds , while the exact position x within is unknown; we denote it by .
Example 6 (Grey Number: monthly electric bill).
Before the meter is read, the household estimates the bill will be between $80 and $120. The unknown true amount x is modeled as the grey number
1.7. Granular Numbers
A granular number encodes a connected set of possible values, typically as center and radius, optionally weighted, capturing structured imprecision [
48,
49,
50,
51].
Definition 10 (Granular Number(G-number)). A granular number is an extension of an ordinary number: instead of a single value, it denotes a connected set of possible values. A unified representation uses a center and radius, , optionally augmented by a granule weight as .
Example 7 (Granular Number: thermostat comfort band).
An office targets C with a tolerated band of C and sensor reliability weight . As a granular number,
representing the connected set with weight .
1.8. Interval Number
An interval number is a closed real interval
, representing all possible values between both lower and upper bounds, inclusively [
52,
53].
Definition 11 (Interval Number).
An interval number
is a nonempty closed interval of the real line,
with . The degenerate case identifies with the real number a. Equivalently, one writes with midpoint and half–width
Example 8 (Real-Life Example).
Thermometer with C accuracy reading C: interval .
Commute time estimate between 35 and 50 minutes: interval .
Price quote with possible fluctuation between $480 and $520: interval .
Board length cm with cm tolerance: interval .
1.9. Functorial Numbers
A functorial number assigns each object a commutative semiring naturally, with operations preserved along morphisms[
54].
Definition 12 (Functorial Number).
Let be a category with finite products. A Functorial Number
is a tuple where is a functor, and are natural transformations, such that for each object X, is a commutative semiring, and for every morphism and ,
Equivalently, a Functorial Number is a functor (commutative semirings and homomorphisms), composed with the forgetful functor to .
Example 9 (Free polynomial functor (nontrivial)).
Let (which has finite products). Define
the commutative polynomial semiring with variables indexed by the set X; addition and multiplication are the usual polynomial + and ·, and
For a function , let be the unique semiring homomorphism sending each variable to the variable and acting linearly/multiplicatively on monomials. Then for all ,
Hence and define a functor (and thus a Functorial Number).
Concrete calculation.
Let , , and with . For ,
Example 10 (Constant natural-number semiring (simple but fully functorial)).
Let be any category with finite products. Define the constant
functor by for every object X, and for every morphism f. Give each the standard commutative semiring structure
Then for all in and ,
Thus N factors as , so it is a Functorial Number (a functor into followed by the forgetful functor).
1.10. Hyperstructure and SuperHyperStructure
Many mathematical and real-world concepts exhibit inherently hierarchical structures. To capture and represent such multi-level relationships in a clear and systematic way, the notions of
hyperstructure and
superhyperstructure have been introduced. A
hyperstructure generalizes a classical algebraic structure by replacing the underlying set
S with its powerset
; hyperoperations then combine subsets into (possibly new) subsets, enabling the expression of higher–order relations [
55,
56,
57,
58,
59]. Related concepts include HyperFuzzy Sets [
60,
61,
62], HyperAlgebras [
63,
64], Chemical HyperStructure [
65,
66,
67,
68,
69], and HyperGraphs [
70,
71,
72,
73].
Definition 13 (Base set).
[74] Let S be a nonempty set, called the base set
. Equivalently,
All further constructions—such as or its iterates —are formed from elements of S.
Definition 14 (Powerset).
[75] The powerset
of a set S, denoted , is the collection of all subsets of S:
including both the empty set ∅ and S itself.
Definition 15 (Hyperoperation).
(cf. [57,76,77]) A hyperoperation
is a generalization of a binary operation in which the result of combining two inputs is a set
(not necessarily a singleton). Formally, for a set S, a hyperoperation ∘ is a map
Definition 16 (Hyperstructure). (cf. [
78,
79,
80,
81,
82])
A hyperstructure
replaces the base set S by its powerset and is given by where ∘ is a hyperoperation acting on subsets of S (i.e., ). This framework allows one to combine collections of elements into other collections.
Example 11 (Hyperstructure — Team Skills with Emergent Capabilities (real-life)).
Base set. Let where =frontend, =backend, =data science, =devops, =API integration, =ML operations, =full–stack capability.
Synergy map. Define by
and otherwise. Extend to subsets by
Then is a hyperstructure.
Concrete composition. For
we get
Thus combining two teams (skill sets) yields a set of attainable capabilities, including emergent ones .
Example 12 (Hyperstructure — Document Tagging with Cross-Topic Emergence).
Base set. Let
Cross-tag rule. Define by
and (symmetrically) . For let the hyperoperation
Concrete composition. If a report has tag set
then
so promotes emergent cross-tags
(e.g. ) when topics are combined.
A
SuperHyperStructure extends the concept of a hyperstructure by recursively applying the powerset construction
n times. In this framework, operations act on nested collections, thereby enabling the modeling of hierarchical, multi-level interactions [
57,
59,
83,
84,
85,
86]. Related notions in the literature include the
SuperHyperGraph [
87,
88,
89] and the
SuperHyperUncertain Set [
90,
91,
92,
93].
Definition 17 (Iterated powersets).
(cf. [64,78,83,94]) For , define recursively
Similarly, the nonempty
iterated powersets are where .
Definition 18 (SuperHyperOperation).
[78] Let H be a nonempty set. Define recursively, for each integer ,
Fix . An -SuperHyperOperation
is a map where denotes the n-th iterated powerset of H, either excluding the empty set (classical type) or including it (Neutrosophic type). In the former case we call a classical-type
-SuperHyperOperation
; in the latter, a Neutrosophic
-SuperHyperOperation.
Definition 19 (SuperHyperStructure of order
).
(cf. [57,95,96,97]) Let S be a nonempty set and . A -SuperHyperStructure
on S of arity k is a map
When and , this recovers an ordinary k-ary operation on S; when , , it is a k-ary hyperoperation; and when , it is an -superhyperfunction.
Example 13 (SuperHyperStructure — Weekly Meal Planner (m=1, n=2, k=2)).
Base set. Let the set of dishes be
We build (sets of dishes) and (sets of menus, each menu being a set of daily dish-sets).
Operation. Define
that maps two inputs A (available/preferred dishes) and B (supplemental/rotation dishes) to a set of weekly menus
. For example, with set
and define
Type check. Domain and codomain match the SuperHyperStructure specification; here .
Example 14 (SuperHyperStructure — Software Release Blueprints (m=1, n=2, k=2)).
Base set. Let features/modules be
Then are feature sets (candidate bundles), and are sets of blueprints (each blueprint is a set of bundles, e.g. per milestone).
Operation. Define
where input are core
features and are optional
features. For instance
Construct two blueprints (milestone plans):
Each blueprint is a set of sets of features (e.g. phases), so ★ indeed maps , a concrete SuperHyperStructure capturing hierarchical release planning.
2. Review and Results: Some Uncertain Number
This section investigates the concept of the Uncertain Number and explores whether it can be extended to define both the Ordered Uncertain Number and the Ranking Uncertain Number.
2.1. Ordered Neutrosophic and Plithogenic Number
An ordered neutrosophic number comprises three ordered membership curves for truth, indeterminacy, and falsity, producing convex, levelwise reconstructed degree functions. An ordered plithogenic number collects ordered membership curves per attribute, aggregating them via contradiction-aware operators to yield an ordered curve.
Definition 20 (Ordered Membership Curve).
A pair of continuous functions is an ordered membership curve
if
It induces a (normal, convex, u.s.c.) fuzzy membership by the standard inverse–α–cut reconstruction
Definition 21 (Ordered Neutrosophic Number (ONN)).
An ordered neutrosophic number
is a triple where each is an ordered membership curve (Def. 20). Writing for the reconstructed memberships, the associated (single–valued) neutrosophic number on is the triplet of degrees with the usual neutrosophic bound for all .2
Example 15 (Ordered Neutrosophic Number — Safe cruising speed on a wet highway).
Let the universe be the speed (km/h). We model the neutrosophic triplet of (T) safe
, (I) context–dependent
, and (F) unsafe (too fast)
degrees by ordered membership curves (Def. 20), each yielding a normal, convex fuzzy set via inverse α–cuts:
(T) Safe speed. Triangular OFN with support , mode 75:
(I) Context dependence (traffic/spray variability). Trapezoid with “core” and support :
(F) Unsafe (too fast). Triangular OFN with support , mode 120:
Each is nondecreasing, nonincreasing, and , so is an ONN (Def. 21). A numerical readout at km/h:
whence and as required.
Theorem 1 (ONN generalizes OFN).
Let be the class of OFNs and the class of ONNs. The assignment
is an injective embedding for any fixed admissible
choices of: (i) a constant “null” curve with (crisp point ), and (ii) a complement curve representing a chosen fuzzy complement of .3 Moreover, the projection
satisfies .
Proof. For any OFN , is an ONN by Definition 21, since each component is an ordered curve. If , then their T –components coincide, hence ; thus is injective. By construction, , so . Therefore every OFN appears as a special case of an ONN (with fixed neutral/complement components), i.e. ONN generalizes OFN. □
Definition 22 (Ordered Plithogenic Number (OPN)).
Fix a (finite) set V of attribute values and a symmetric contradiction degree
with . An ordered plithogenic number
is a tuple where each is an ordered membership curve (Def. 20), and is a levelwise aggregation scheme producing either
- (i)
an aggregated
OFN by continuous, monotone maps with for all y, or
- (ii)
the family view together with as part of the structure.
Typical choices are t–norm/t–conorm–based mixtures whose weights depend on c (e.g., more conorm when contradiction is higher). Monotonicity of in each argument guarantees that is an OFN whenever the are.
Example 16 (Ordered Plithogenic Number — Daily salt intake aggregated across stakeholders). Let be daily sodium intake (mg). We consider : a cardiologist, an athletics coach, and a chef. Each provides an ordered membership curve encoding the acceptability of x for that perspective; the family together with a contradiction map c and a levelwise aggregator forms an OPN (Def. 22).
Shapes: Cardio—triangular (mode 1500); Coach—trapezoid (core ); Chef—trapezoid (core ).
Contradiction degrees. Symmetric with ; for instance
Set the global mixing weight .
Levelwise aggregation. Define monotone maps (for each )
Then is an aggregated OFN, and
is an ordered plithogenic number.
Numerical slice at .
Thus , , and
Hence the aggregated α–cut at level is mg. For an intake mg, , so the aggregated membership satisfies , illustrating how contradiction–aware aggregation yields a single ordered fuzzy number summarizing the stakeholders’ views.
Theorem 2 (OPN generalizes OFN).
Let be the class of OPNs and the class of OFNs. The map
is an injective embedding whose aggregated view returns .
Proof. With a singleton attribute set , zero contradiction, and identity aggregation, Definition 22 reduces to the given OFN. Injectivity is immediate. The aggregated curve is by construction. □
Theorem 3 (OPN generalizes ONN).
Let be the class of ONNs and the class of OPNs. There is an injective embedding
for any fixed contradiction map c on (e.g. user–specified). In the family view, κ is the identity on components.
Proof. Take and place the three ordered curves of the ONN as the attribute–indexed family. With identity aggregation, Definition 22 reproduces exactly the ONN data. Distinct ONNs yield distinct families, hence injectivity. □
2.2. Ordered Rough Numbers
An ordered rough number maps indices to rough intervals from lower and upper approximations, using averages along an increasing chain.
Definition 23 (Rough model and notation).
Let U be a nonempty finite universe, an equivalence (indiscernibility) relation with quotient (granules) , and let be a numeric attribute (valuation). For , the lower/upper
E –approximations
are
For a nonempty finite , write The (interval–valued) rough number
induced by A is
whenever and are nonempty.4
Definition 24 (Ordered Rough Number (ORN)).
Fix a totally ordered index set I (e.g. ). An ordered rough number
on is specified by an increasing chain of target sets
, , with and such that for all i. Its ordered interval profile
is the pair of maps
and we write
Each section is the rough number associated to .
Example 17 (Ordered Rough Number — Delivery-time thresholds with explicit calculations).
Consider parcel deliveries from three suppliers over one week. Universe lists all recorded deliveries; the equivalence relation E groups deliveries by supplier into granules:
Let be the door–to–door delivery time (minutes) with values
Define an increasing chain of target sets by delivery–time thresholds
For each i, compute lower/upper E-approximations and the ordered rough interval
1) Level (): .
2) Level (): .
so
Thus .
3) Level (): .
Collecting the ordered rough profile
As the threshold increases, both endpoints are nondecreasing, illustrating the ordered rough number defined by this real logistics scenario.
Theorem 4 (Rough-number structure at each index). Let be an ordered rough number on . For every , the interval equals in the sense of Definition 23. Hence an ORN is a family of (ordinary) rough numbers indexed by I.
Proof. By Definition 24, and whenever both approximations are nonempty. This is exactly the construction of in Definition 23. □
Theorem 5 (Monotonicity under threshold chains). Assume the following compatibility conditions:
- (a)
Classwise constancy: f is constant on each E–class (i.e., ).
- (b)
Threshold chain: There exist real numbers such that
Then for the ordered rough number we have, for all ,
In particular, is coordinatewise nondecreasing.
Proof. By classwise constancy, if a class
C intersects
then
, because all elements of
C share the same
f –value. Hence
, where
denotes the (common) value on
C. Consequently,
As i increases, the indexing threshold increases, so the union above is nested: Moreover, every newly added class C satisfies , hence (the last inequality holds because all values in are ). Averages over finite sets are monotone under adding elements whose value is at least the current average, therefore and, since for all i, also □
2.3. Ordered Granular Numbers
An ordered granular number is a sequence of granular intervals, indexed monotonically, whose endpoints vary consistently, forming inclusion-nested uncertainty bands.
Definition 25 (Ordered Granular Number (OGN)).
Let be a nonempty totally ordered index set (e.g. ). An ordered granular number
is a family such that each section is a granular number. We call inclusion–monotone
if for all ,
(Equivalently, .)
Example 18 (Ordered Granular Number — Project budget with widening contingency).
A software project maintains an inclusion–nested sequence of budget bands (center ± radius), each with a confidence weight . Let the baseline estimate be USD. Define the ordered granular family by
Each granular section is the closed interval Hence
We have strict nesting . The inclusion–monotonicity condition holds for all because the center is constant (left side ) and radii increase (right side ). Endpoint monotonicities follow:
Thus
is an ordered granular number representing increasingly conservative budget bands with decreasing confidence weights, a common real-life planning practice.
Theorem 6 (Granular structure of an OGN). Let be an ordered granular number. Then, for every , its section is a granular number. Hence an OGN is a family of granular numbers indexed by I.
Proof. By Definition 25 each component is, by construction, a closed ball in , i.e. a granular number. The conclusion follows immediately. □
Theorem 7 (Nested chain and endpoint monotonicity).
Assume is inclusion–monotone in the sense of (1). Then for all ,
Consequently, the left endpoints form a nonincreasing map () and the right endpoints form a nondecreasing map ().
Proof. The inclusion is exactly (
1) rewritten for intervals. If
then
and
, yielding the endpoint monotonicities. □
2.4. Ordered Functorial Numbers
An ordered functorial number is a diagram of semiring-valued functors with natural, order-indexed embeddings, preserving operations across objects and morphisms.
Definition 26 (Commutative semirings and functor category). Let denote the category of commutative semirings (objects) and semiring homomorphisms (arrows). Let I be a (small) totally ordered set, viewed as a thin category. The functor category has as objects the I-diagrams and as arrows the natural transformations.
Definition 27 (Ordered Functorial Number (OFN)).
Fix a base category with finite products and a total order I. An Ordered Functorial Number
is a functor
Equivalently, it is the same data as a family of Functorial Numbers together with, for all in I, a natural transformation of functors (in X)
whose components are semiring homomorphisms, satisfying and for . If each component is a monomorphism in , we say the OFN is inclusion–monotone.
Example 19 (Ordered Functorial Number — Household shopping baskets over months).
Let the base category be and the index (time) order be (months). Define an Ordered Functorial Number (Def. 27) by taking, for every set X,
with + and · the usual polynomial addition/multiplication, and with
(so the diagram is inclusion–monotone via identities). For a function , let be the unique semiring homomorphism that renames variables ; this makes a functor into .
Concrete data.
Take a two-SKU set and record two monthly “basket polynomials”
Pooling baskets corresponds to semiring addition:
Bundling (e.g., counting ordered pairs of items) corresponds to semiring multiplication:
where commutativity merges the mixed terms.
Naturality check (category aggregation).
Let and map both SKUs to . Then
so
and
Thus semiring operations and the time-indexed embeddings are preserved along f, as required by an Ordered Functorial Number.
Theorem 8 (OFN carries Functorial Number structure at every level).
Let be an OFN and let be the evaluation functor at . Then the composite
is a Functorial Number for every . Moreover, for the morphism is a natural transformation whose components are semiring homomorphisms.
Proof. By functoriality of and of evaluation, is a functor into , hence a Functorial Number. Naturality and the semiring-hom property of are inherited from the arrow part of the diagram for each X. □
Definition 28 (Ambient semirings for classical ordered models). We shall use the following commutative semirings:
- (a)
The pair semiring with componentwise + and · and units , .
- (b)
The triple semiring with componentwise + and ·.
- (c)
For a poset (thin category) J, we write for J-diagrams in .
Theorem 9 (OFN generalizes ordered fuzzy numbers). The assignment defines a faithful embedding from ordered fuzzy numbers into OFNs with designated sections over .
Proof. Given one recovers A by , . Morphisms (e.g. equality) are preserved and reflected because the diagram is constant and sections determine A pointwise in y. □
Theorem 10 (OFN generalizes ordered neutrosophic numbers). The mapping embeds ordered neutrosophic numbers into OFNs with designated sections over .
Proof. As above, N is recovered from componentwise. Faithfulness follows because equality of sections implies equality of the three curves . □
Theorem 11 (OFN generalizes ordered rough numbers). The assignment embeds ordered rough numbers into OFNs with designated sections over .
Proof. Pointwise recovery , yields faithfulness. The order on J is carried by the index category . □
2.5. Ranking Neutrosophic and Plithogenic Number
Let be the universe of real evaluations, endowed with a probability weight such that . All functions below are assumed measurable and bounded.
Definition 29 (Ranking Neutrosophic Number (RNN)).
(cf.[98,99,100]) Fix a continuous neutrosophic kernel
that is nondecreasing in T, nonincreasing in I and in F. Define the neutrosophic score
and the induced preorder .
Example 20 (Ranking Neutrosophic Number — Hiring two candidates with explicit scoring).
Let be three evaluation contexts, with uniform weight . For a single-valued neutrosophic number on X, use the ranking kernel which is nondecreasing in t and nonincreasing in (so it fits Def. of RNN). The score is
Ranking: , so under this neutrosophic ranking.
Theorem 12 (RNN generalizes Ranking Fuzzy Number).
Let be given by a satisfaction kernel s as above. Choose any and define
Then for every fuzzy number A,
hence the restriction of to coincides with .
Proof. For we have . Pointwise, . Integrating against w yields . Therefore iff iff iff . □
Definition 30 (Ranking Plithogenic Number (RPN)).
Fix a continuous plithogenic kernel
which is nondecreasing in the coordinates of beneficial
attributes and nonincreasing in the coordinates of adverse
attributes (as declared by the modeler), and depends continuously on c. Define the plithogenic score
and the induced preorder .
Example 21 (Ranking Plithogenic Number — Smartphone choice with contradiction-aware score).
Consider attribute values , where Battery and Camera are beneficial
and Price is encoded as cheapness
(higher is better). Let be a single usage context with , so the integral reduces to a point evaluation. Use the plithogenic kernel with weights and . Contradiction degrees (symmetric, ):
Phone P.
Scores (in ):
Ranking: , hence under the plithogenic ranking with contradiction awareness.
Theorem 13 (RPN generalizes RNN). Let and, given a neutrosophic number , form the plithogenic instance with and any contradiction c satisfying and . Choose Ψ such that for all one has . Then and hence restricted to the image of this embedding coincides with .
Proof. By the stated choice of , pointwise . Integrating against w yields ; the induced preorders match. □
Theorem 14 (RPN generalizes Ranking Fuzzy Number). Embed a fuzzy number A as a plithogenic instance with either
- (a)
and , or
- (b)
, , , and .
Choose Ψ so that in case (a), or in case (b). Then and restricted to these embeddings coincides with .
Proof. In case (a), pointwise equality gives . In case (b) we again have , hence the same identity; preorders coincide because both compare the same real scores. □
2.6. Ranking Rough Number
Ranking Rough Number assigns a monotone score to a rough number’s endpoints, inducing a total preorder while preserving the underlying rough-number interval structure.
Definition 31 (Ranking Rough Number (RRN)).
Fix a continuous scoring kernel that is nondecreasing in each argument. For a rough number (with ), define its ranking score
The induced preorder on rough numbers is
Typical choices include the convex/penalized form with , .
Example 22 (Ranking Rough Number — Choosing a shipping policy from rough delivery times). We compare two shipping policies (Priority vs. Economy) using rough numbers built from a small, real dataset.
Data and indiscernibility. Universe are 10 recent deliveries with door-to-door delays (minutes). Deliveries are indiscernible by courier (equivalence classes):
Totals: , , hence .
Lower/upper E–approximations:
Rough numbers with , :
Compute , hence
Ranking kernel and scores. Use the monotone, penalized midpoint
Priority:
Economy:
Since , we have
so Priority
is preferred (smaller/faster and tighter).
Theorem 15 (RRN retains the rough-number structure).
For every , the object has as its first component a rough number computed from and . Consequently, the collection of all RRN’s projects onto the class of rough numbers; i.e., forgetting the score recovers exactly the standard rough-number structure.
Proof. By construction, and are computed from the lower/upper approximations , under the same and attribute . Hence satisfies the definition of a rough number. The added scalar does not modify nor , therefore the first component of is exactly . The projection maps the class of RRN’s onto the class of rough numbers, establishing the claim. □
Lemma 1 (Order consistency under endpoint dominance). Let and be rough numbers with and . If φ is nondecreasing in each argument, then
Proof. Monotonicity of yields , hence the asserted preorder relation. □
2.7. Ranking Granular Numbers
Ranking Granular Numbers maps each granular number’s center, radius, and weight to a score, yielding a preference order without altering granular content structure.
Definition 32 (Ranking Granular Number (RGN)).
Fix a continuous scoring kernel
that is nondecreasing in c, nonincreasing in r, and nondecreasing in A. For a granular number , define its ranking score
The induced preorder on granular numbers is
Typical choices include risk–penalized, weight–rewarded scores, e.g. with , or for symmetric intervals.
Example 23 (Ranking Granular Number — Picking a phone by battery-life band).
Two phones report lab-tested battery life as granular numbers (center ± radius, with reliability weight A). Let the monotone score be which is nondecreasing in c and A, and nonincreasing in r.
Phone M. Battery band hours, weight .
Phone N. Battery band hours, weight .
Since is false and , we obtain
Phone M ranks higher: larger center (expected life), acceptable uncertainty, and stronger reliability weight.
Theorem 16 (RGN retains the granular-number structure).
For any granular number , the object
has as its first two components exactly the underlying granular number (and its weight). Consequently, the projection maps the class of all RGNs onto the class of granular numbers; forgetting the score recovers the original granular-number structure.
Proof. By definition, is the connected value set of X and its weight. The scalar is computed from and does not alter the set nor the weight. Hence the first (two) component(s) of coincide(s) with the given granular number (and its weight). The projection is therefore surjective onto , establishing that RGNs retain the granular-number structure. □
Definition 33 (Benefit dominance on granular numbers).
We say benefit-dominates
, written , if
Lemma 2 (Order consistency under dominance). If and φ is nondecreasing in c, nonincreasing in r, and nondecreasing in A, then .
Proof. From
,
,
and the monotonicity of
,
i.e.
, hence
. □
2.8. Ranking Functorial Numbers
Ranking Functorial Numbers adds a natural scoring transformation to functorial-number semirings, comparing elements consistently across objects and morphisms while retaining algebraic operations unchanged.
Notation 17 ((Recall) Functorial Number).
Let be a category with finite products. A Functorial Number
is a functor (the category of commutative semirings and homomorphisms). Writing for the forgetful functor, we set , so that each object carries a commutative semiring
and for every in , is a semiring homomorphism.
Definition 34 (Ranking Functorial Number (RFN)).
Fix a totally preordered set (e.g. ) and let be the constant functor at the set S. A Ranking Functorial Number
on is a pair where and is a natural transformation (i.e. for all , ). Each component is called a ranking functional
on and induces a total preorder
We say that ρ is monotone w.r.t. the semiring order if, whenever carries a designated preorder compatible with (e.g. a pointwise, cutwise, or dominance order), then implies .
Example 24 (Ranking Functorial Number — Revenue ranking for coffee shop menus with category aggregation).
Let be the small category with two objects X (SKUs) and Y (categories), and a single non-identity arrow that aggregates
SKUs into categories. Concretely,
Functorial number. Define by
the commutative polynomial semirings, and for let
be the unique semiring homomorphism that renames
variables along f (i.e., sends a monomial in X to the corresponding monomial in Y by replacing each SKU by its category). Write for the underlying-set functor.
Ranking functional (natural in X ). Fix prices per category
and induce SKU prices by pullback , i.e.,
Define for each object a ranking functional
i.e., take only the degree-1 part
(linear terms) of P and multiply by the corresponding prices. Then the pair is an RFN with and the usual order: for the unique non-identity f we have the naturality identity
because renaming variables along f preserves linear coefficients, and .
Two menus and their scores. Consider two candidate daily menus as (linear) polynomials in :
SKU-level ranking (in
X ):
Hence at SKU level.
Naturality check via category aggregation. Applying collapses SKUs to categories:
Now evaluate in Y:
which matches the SKU-level scores, confirming .
Since , the RFN ranks higher than :
Thus, regardless of working at the SKU level or the aggregated category level, the same revenue-based ranking is obtained—exactly the naturality property required of a Ranking Functorial Number.
Theorem 18 (RFN carries the Functorial-Number structure). Let be a Ranking Functorial Number. Then the projection onto forgets only the scoring and leaves intact the commutative semiring data. In particular, is a Functorial Number, and with its is unchanged by adding ρ.
Proof. By definition, consists of the functor together with a natural transformation . The semiring structure on each fiber and the homomorphism property of are supplied solely by , independent of . Hence forgetting yields exactly the underlying Functorial Number. □
Assume has a terminal object . Writing :
Definition 35 (Fuzzy, neutrosophic, rough fibers at ).
- (a)
Fuzzy fiber. Let be a chosen class of fuzzy numbers on endowed with a commutative semiring structure via any standard construction (e.g. α-cut Minkowski sum/product with Dirac as units). A ranking fuzzy number is a map inducing a total preorder.
- (b)
Neutrosophic fiber. Let be a class of (single-valued) neutrosophic numbers with well-defined (e.g. component-wise t-conorm/t-norm with neutral elements). A ranking neutrosophic number is a map inducing a total preorder.
- (c)
Rough fiber. Let be (a subclass of) rough numbers, e.g. intervals with , operations given by Minkowski arithmetic, and units , . A ranking rough number is a map .
Theorem 19 (RFN generalizes fuzzy/neutrosophic/rough rankings). Let be an RFN on and let be terminal.
- (i)
(Fuzzy) If and , then ρ restricted to is exactly a ranking of fuzzy numbers.
- (ii)
(Neutrosophic) If and , then ρ restricted to is exactly a ranking of neutrosophic numbers.
- (iii)
(Rough) If and , then ρ restricted to is exactly a ranking of rough numbers.
Conversely, any classical ranking in (i)–(iii) extends to an RFN by taking a constant functor (on objects) with the chosen semiring fiber at and defining ρ to be constant-on-morphisms with component equal to the given ranking.
Proof. For (i)–(iii), evaluation at the terminal object gives the component , which is, by hypothesis, precisely the corresponding classical ranking map. Naturality imposes no further constraint at (there is a unique arrow ), so the induced preorder on is exactly the classical one.
For the converse, given any ranking map on a chosen semiring fiber M (e.g. , , or ), define to be the functor that sends every X to the same semiring M and every f to the identity homomorphism on M. Define for all X. Then for every f, so is natural. Hence is an RFN whose terminal component is the given classical ranking. □
Lemma 3 (Monotonicity transport). Suppose each is equipped with a preorder compatible with (e.g. dominance for intervals, cutwise order for fuzzy numbers, componentwise order for neutrosophic numbers), and is monotone w.r.t. these preorders. If ρ is monotone w.r.t. for each X, then for all and one has so functorial transport preserves ranking inequalities.
Proof. By monotonicity of and , . □
3. Additional Review and Results: Some HyperUncertain Number
3.1. HyperInterval and SuperHyperInterval Number
A HyperInterval Number is a set-valued generalization of interval numbers, closed under hyperoperations, robustly modeling uncertainty via hyperstructural subset combinations. A SuperHyperInterval Number organizes hyperintervals within iterated powersets, combining them through superhyperoperations, thereby generalizing hyperinterval numbers for hierarchical, multi-level uncertainty.
Notation 20.
Let
be the set of all (nonempty, closed) real intervals. For set
These are the classical interval–arithmetic sum/product (the outer or convex hulls of the pointwise sum/product sets and ).
Definition 36 (HyperInterval Number and basic hyperoperations).
A HyperInterval Number
is an element of considered inside the following hyperstructure: where, for ,
Equivalently, (resp. ) is the set of all closed subintervals of the classical interval sum (resp. product) hull.
Example 25 (HyperInterval Number — Grocery Trip Duration with Choice Sets). A shopper plans a quick grocery run. Two independent choices create uncertainty bands:
Travel time (route choice):
Checkout time (lane choice):
Each set is a HyperInterval Number (). The total time is the hyperaddition
Evaluating the Minkowski sums gives four concrete intervals:
Thus, the day’s “total trip time” is not a single interval but a set of intervals reflecting route/checkout combinations. Operations such as adding a fixed “parking search” buffer minutes simply hyperadd that interval to each element of .
Theorem 21 (HyperInterval Numbers form a hyperstructure). With from Definition 36, each map is well-defined and never empty; hence is a (binary) hyperstructure.
Proof. Fix . By construction, and every closed subinterval again lies in ; thus and is nonempty (since it contains ). The same argument applies to ⊠ using . □
Theorem 22 (HyperInterval Numbers generalize Interval Numbers).
Define selectors
Then and for all . Moreover, for degenerate intervals (identified with ),
Hence the classical interval arithmetic (and, as a special case, real arithmetic) is obtained by selecting a distinguished element from each hyperresult; in this precise sense, HyperInterval Numbers generalize Interval Numbers.
Proof. By Definition 36, , so ; similarly for ⊠. When and , and , yielding the claim. □
Definition 37 (SuperHyperInterval Number and superhyperoperations).
Write . A SuperHyperInterval Number
is an element (a nonempty family of intervals). Define the superhyperoperations
by
Thus each output is a set of nonempty sets of intervals , i.e. an element of .
Example 26 (SuperHyperInterval Number — Commute Time Under Weather Scenarios).
A commuter’s one-way time depends on both route choice
and weather scenario
. For each scenario, we first obtain a HyperInterval
of route-dependent intervals:
| Clear (Scenario ): |
Rain (Scenario ): |
|
|
The SuperHyperInterval
collecting these scenario-wise HyperIntervals is
If we also have a stopover
option (e.g., coffee pickup) modeled by another HyperInterval minutes, then the set of scenario-aware total times
is obtained via superhyperaddition:
Thus each scenario (clear vs. rain) yields its own set of feasible intervals for total travel time, preserving the hierarchy (scenario → route choices) inherent in real-life decision making.
Theorem 23 (SuperHyperInterval Numbers form a
–SuperHyperStructure).
Let . The pair of maps
from Definition 37 endows S with a two–ary SuperHyperStructure (cf. the general Definition of SuperHyperStructure in the preliminaries).
Proof. Given nonempty and any , Theorem 21 yields and . Therefore the images and are nonempty subsets of , i.e. elements of , as required. □
Theorem 24 (SuperHyperInterval Numbers generalize HyperInterval Numbers).
Let be the singleton embedding and let be the (set-theoretic) union . Then for all ,
Consequently, the HyperInterval hyperstructure is recovered from the SuperHyperInterval structure by singleton embedding followed by Unwrap, so SuperHyperInterval Numbers generalize HyperInterval Numbers.
Proof. By Definition 37, and . Taking unions gives and . □
3.2. HyperGranular and SuperHyperGranular Number
This section introduces two new uncertainty numbers. First, the HyperGranular Number (HGN) equips the class of granular numbers with a hyperoperation, thereby forming a hyperstructure in the sense of hyperalgebra. We prove that HGNs strictly generalize classical granular numbers. Second, the SuperHyperGranular Number (SHGN) lifts HGNs to iterated powersets and endows them with an -superhyperoperation, forming an - SuperHyperStructure. We prove that SHGNs strictly generalize HGNs.
Remark 1.
Recall the (weighted) granular number
which represents the connected set (interval)
optionally annotated with a weight . Let
be the carrier of all (weighted) granular numbers. Classical (deterministic) granular arithmetic uses the Minkowski sum
where, for definiteness, we take the weight-combiner (any fixed t-norm would also work).
Definition 38 (HyperGranular Number and its hyper-sum).
A HyperGranular Number
is any element of the carrier . Define a hyper-sum
by
Example 27 (HyperGranular Number — “Drive + Parking/Walk” Total Time).
Setup. A commuter models two granular components (minutes):
Here c is the typical time, r is the tolerance (half–width), and is a confidence/weight. For concreteness, take the weight-combiner to be the product: .
Hyper-sum. By Definition 38, the total time is the set
Each element represents a feasible total-time band minutes. The minimal radius () corresponds to strongly correlated or partially overlapping uncertainties (conservative propagation), while the maximal radius () corresponds to full, independent accumulation.
Remark 2.
While the classical Minkowski sum fixes the radius to , the hyper-sum returns all admissible radii between a conservative bound and the maximal propagation . Hence, is a set of granular results, not a single one.
Proposition 1 (Closure and interval image).
For all , ; in particular, every element of is of the form with . Moreover,
so the left/right endpoints vary linearly
with ρ.
Proof. By Definition 38, and , hence each produced triple is in . The interval formula follows from the definition of . □
Definition 39 (Lift to sets).
For , define the set-lift
of by
Theorem 25 (HGNs carry a hyperstructure).
The pair is a hyperstructure
:
Proof. By Definition 39, maps two subsets of to a union of subsets of , hence again a subset of . Thus has type , which is exactly the requirement (cf. Hyperstructure definition in the preliminaries). □
Theorem 26 (HGN generalizes the classical Granular Number).
Let be the singleton embedding . Define a selector
that, for any nonempty of the form in Proposition 1, picks the element with the maximal
radius . Then, for all ,
Hence, classical granular arithmetic is recovered as a determinization (selection) of the HGN hyper-sum, and HGNs strictly generalize granular numbers.
Proof. By Definitions 38 and 39, is exactly the set of with . Selecting the unique element with yields the classical Minkowski-type result . The map is injective, so the generalization is strict. □
We now lift HGNs to the iterated powerset universe and define an -superhyperoperation.
Definition 40 (Iterated wrap/flatten).
For define the wrap
(singleton nesting)
For a nested set (the m-fold powerset), define the flatten
map to atoms
Definition 41 (SuperHyperGranular Number and
-superhyper-sum).
Fix integers and . An -level SuperHyperGranular Number
is an element of . Define the binary
-superhyper-sum
by
Example 28 (SuperHyperGranular Number — Morning Block Under Weather Scenarios).
We consider two scenario families, each a set of granular options
(thus elements of ):
Collect them into level-2
SuperHyperGranular Numbers (sets of sets):
We use the product for weight-combination and apply the superhyper-sum
from Definition 41:
Representative outputs. Flattening exposes the granular options; pairing any breakfast option X with any commute option Y and hyper-adding yields a wrapped set-of-sets result. Two illustrative pairs:
(i) Fair
Fair.
, . Then , , and . Thus
i.e. a level-2 object whose inner set encodes all feasible morning-block bands minutes.
(ii) Rain
Rain.
, . Then , , and . Hence
capturing heavier-uncertainty morning blocks under rain.
The full collects all such wrapped hyper-sums over the flattened option sets, preserving the scenario hierarchy (sets of option-sets) while propagating uncertainty via the HGN hyper-sum. Each wrapped component is a family of granular bands whose radii range from conservative coupling () to full accumulation ().
Theorem 27 (SHGNs carry an
-SuperHyperStructure).
For every , the pair is an - SuperHyperStructure
(cf. SuperHyperStructure definition in the preliminaries).
Proof. By Definition 41, the output consists of with , hence each output element lies in . Therefore has the required type . No further algebraic axiom is needed for the existence of a SuperHyperStructure. □
Theorem 28 (SHGN generalizes HGN).
Fix . Define the embedding by . For all ,
In particular, if removes n layers of wrapping and is the selector from Theorem 26, then
Hence SHGNs strictly generalize HGNs.
Proof. By Definition 41, when
and
we have
and
. Thus
Applying sends each element to , and the selector then returns by Theorem 26. Injectivity of is clear, so the generalization is strict. □
3.3. Granular Set, HyperGranular Set and SuperHyperGranular Set
We formalize Granular Set, HyperGranular Set, and SuperHyperGranular Set and show that each carries, respectively, the structure of a Granular Number (GN), HyperGranular Number (HGN), and SuperHyperGranular Number (SHGN).
Notation 29 (Carrier of granular numbers).
Let
Each represents the connected set (interval) , optionally annotated with weight a. The classical (deterministic) granular sum is
The hypergranular sum is as in Def. 38: Write for the family of nonempty subsets.
Definition 42 (Granular Set).
A Granular Set
is a nonempty set of granular numbers, i.e. an element . Its extent
is
Define the granular–set sum
Example 29 (Granular Set — Menu Design with Calorie Bands).
Setup. Each dish is a granular number whose extent
is the calorie interval . Consider two dish families (nonempty subsets of ):
Then and .
Granular–set sum (Def. 42). Using the deterministic granular sum , we get
Extents. and . Hence
matching the Minkowski sum of extents (Theorem 30). Operationally: the two entree choices paired with the side yield two feasible menu-calorie bands, each with a clear center, radius, and confidence.
Theorem 30 (Granular Sets carry GN structure).
is closed and, via the singleton embedding , , one has
Hence Granular Sets carry (and extend by union) the deterministic GN operation. Moreover,
the (outer) Minkowski sum of extents.
Proof. Closure is immediate from the definition: for , , , so the resulting collection is nonempty. The singleton statement is tautological. The extent identity follows from and distributing union over pairwise sums. □
Remark 3 (Associativity and units). Because ⊞ on is associative with unit , the induced is associative with unit . (Proof: pointwise on generators.)
Definition 43 (HyperGranular Set).
A HyperGranular Set
is again an element of , but endowed with the hyper–set sum
Thus, given two granular sets, we return all nonempty subfamilies of the pairwise hyper–sum union.
Example 30 (HyperGranular Set — Commute Planning with Flexible Coupling).
Setup. Let denote minutes with confidence a, center c, radius r. Define granular choice sets
Hyper–set sum (Def. 43). For each pair , the hyper-sum
(Def. 38) returns all
granular results
Thus (Def. 43) consists of all nonempty subfamilies M drawn from the union of these four hyper-sum bands.
A concrete member . Selecting the maximal
coupling radius in each pair (i.e., ) yields
Operationally: encodes four feasible total-commute bands under worst-case uncertainty accumulation, one per (drive, park+walk) choice.
Theorem 31 (HyperGranular Sets carry HGN structure).
is a hyperstructure: for each , and is nonempty. Under the singleton embedding ,
so selecting (e.g. by the maximal–radius selector ) an element of this image recovers the HGN result:
Hence HyperGranular Sets generalize both HGNs (by singletons) and GNs (by selection).
Proof. Nonemptiness: for any , , (Def. 38); choose any nonempty subfamily as M. Type: every such M is a nonempty subset of , i.e. an element of S, so the whole output is a subset of S. The singleton and selector statements are immediate from the definitions of and . □
Definition 44 (SuperHyperGranular Set).
Let the base set
be . For and , anm –level SuperHyperGranular Set
is an element of . Define wrap/flatten over
Sby
Define the –superhyper–set sum
by
Example 31 (SuperHyperGranular Set — Scenario Tree for Morning Routine).
Level-1 (granular sets). Breakfast options:
Commute options (weather-dependent):
Level-2 (sets of granular sets). Let be the space of nonempty granular sets. Define
We use the superhyper–set sum (Def. 44):
One concrete branch. Take (breakfast) and (rainy commute). Form the max-radius
selector on the hyper–set sum to obtain
Then is a specific element of .
Interpretation. The level-2 wrapper preserves the scenario hierarchy (“branch = rainy”), while lists the feasible morning-block bands under that branch. Each band is a granular number with explicit center, radius, and confidence, produced by hyper–propagating uncertainty across breakfast and commute choices.
Theorem 32 (SuperHyperGranular Sets carry SHGN structure).
For every , the pair
is an –SuperHyperStructure. Moreover, for the embedding given by and any ,
Applying n–fold unwrapping followed by a selector (e.g. choosing maximal–radius elements in each pair inside M) recovers the deterministic granular–set sum . Hence SHGSs strictly generalize HGSs, which in turn generalize GNs.
Proof. Type: by construction, each output element has the form with , hence lies in , so has the required signature. The displayed identity follows from . Finally, unwrapping yields ; selecting (e.g. by maximal radii inside each contributing HGN) collapses the hyperresult to the deterministic pairwise sums, i.e. . Injectivity of is clear, so the generalization is strict. □
4. Conclusions
This paper developed a unified framework for uncertainty numbers by introducing
ordered and
ranking structures across six paradigms: fuzzy, neutrosophic, plithogenic, rough, granular, and functorial numbers. In future work, we hope to consider extensions that employ HyperRough Sets [
101,
102], HyperSoft Sets [
103,
104,
105], HyperFuzzy Sets [
60,
61,
106], HyperNeutrosophic Sets [
90,
107,
108], HyperPolar Sets [
109], and HyperPlithogenic Sets [
93,
110]. We also intend to investigate extensions based on Graphs [
111,
112], HyperGraphs [
71,
72,
113], SuperHyperGraphs [
89,
114,
115,
116], and HyperAlgebra [
117,
118,
119].
Funding
No external funding was received for this work.
Research Integrity
The author confirms that this manuscript is original, has not been published elsewhere, and is not under consideration by any other journal.
Use of Computational Tools
All proofs and derivations were performed manually; no computational software (e.g., Mathematica, SageMath, Coq) was used.
Code Availability
No code or software was developed for this study.
Ethical Approval
This research did not involve human participants or animals, and therefore did not require ethical approval.
Use of Generative AI and AI-Assisted Tools
We use generative AI and AI-assisted tools for tasks such as English grammar checking, and We do not employ them in any way that violates ethical standards.
Data Availability Statement
This paper is theoretical and did not generate or analyze any empirical data. We welcome future studies that apply and test these concepts in practical settings.
Acknowledgments
We thank all colleagues, reviewers, and readers whose comments and questions have greatly improved this manuscript. We are also grateful to the authors of the works cited herein for providing the theoretical foundations that underpin our study. Finally, we appreciate the institutional and technical support that enabled this research.
Conflicts of Interest
The authors declare no conflicts of interest regarding the publication of this work.
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| 1 |
See, e.g., satisfaction-function ranking and viewpoint dependence; and possibility-theoretic comparisons. |
| 2 |
The bound is automatically satisfied if each is a fuzzy membership; no further coupling among is required here. |
| 3 |
For instance, one may take as the ordered curve of Zadeh’s complement , whenever that complement is again representable by an ordered curve (e.g. for symmetric triangular/trapezoidal cases). Alternatively, any fixed admissible can be used—the embedding does not depend on the particular choice. |
| 4 |
If an approximation is empty, the mean is undefined; throughout we restrict to indices for which both are nonempty. |
|
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