Submitted:
07 March 2026
Posted:
09 March 2026
Read the latest preprint version here
Abstract
In this paper, we consider the properties of the following objects: plafal and geo-space (a general overview). As an application of the created theory, the proof of the equality of complexity classes P and NP will be given.
Keywords:
plafal
; plafale
; the theory of plafales
; P vs NP problem
MSC: Primary: 00-02; 00A05; 68Q15; Secondary: 00A71; 08-00; 18A05; 18A10; 37-00; 54-00; 65D99; 65Y20; 68Q25
1. Introduction
The first edition of [1] is published in March 2011. The publication’s goal is the creation of a new theory in mathematics, where the central object is a plafal1. The second edition of [2] is published in February 2013. After the report at the 42nd Polish Conference on Mathematics Applications [3], it is necessary to create applications based on the theory of plafales. Here we will provide an appropriate overview of the research and development process.
Finite element method. There are created mathematical models of serendipity finite elements: a new approach to construction basis and field functions. A quadruple role of the basis functions of serendipity finite elements is shown [4,5].
IT (finite element method as an algorithmic support). Due to solving the non-standard Dirichlet boundary value problem [4], using the components of the theory of plafales (to obtain the surface of the temperature field in three-dimensional space), there is developed a software for testing non-stationary temperature fields [6].
Cryptography. In September 2014 there is created a symmetric-key algorithm “ECLECTIC-DT-1” [7]. Algorithm’s characteristics: block length is 128 bits, key length is 256 bits, 14 rounds. Let us show the algorithm’s indicators. Upper bounds of practical security: (against differential cryptanalysis [8]), (against linear cryptanalysis [9]). Upper bounds of provable security (for the first four rounds): and .
In December 2018 there is created a symmetric-key algorithm “STEEL” [10]. Algorithm’s characteristics: block length is 128 bits, key length is 256 bits, 14 rounds. Algorithm’s indicators: and .
Note. Editions [1,2] are the bases of the theory of plafales. The paper presents the “linear passage”: all objects are introduced to prove P = NP as soon as possible. The theory has to be taken into consideration starting from this paper.
*Using the deterministic machine, P = NP is performed with pre-prepared tape.
2. Concept of the Plafal
We will use a framework “Standard By Default” [11]. A mathematical entity is described as -standard according to the following rules: a set, monoid, topological space, poset, family, graph, diagram, cardinal, ordinal etc. is standard when it is small; a category, groupoid, multicategory, locally ordered category etc. is standard when it is light; for , an n-category is standard when it is n-moderate. A mathematical entity is described as -standard according to the following rules: an ∞-groupoid is standard when it is small; an -category is standard when it is light; for , an -category is standard when it is n-moderate. A function, relation, subset, functor, natural transformation etc. is always standard.
Plafal
For any simple graph 2 let there be a correspondence between each vertex and -standard, and also between each edge and -standard. The mentioned and can be the same for V and for E respectively. Thus we obtain an object, which is called a plafal and is denoted by or , where i is a number of graph’s vertices, j is a number of graph’s edges. Generally, is called a vertex of the plafal and is denoted by ; is called an edge of the plafal and is denoted by . By we denote a collection of vertices, by we denote a collection of edges. Between and , which are connected by , there is not necessarily a logical relation. If and , then we say that is a trivial plafal and write *. For example, the representation of on a vector space [12] is a type of . Finally, or , where is a collection of and is a collection of .
*-plafal
For any simple graph let there be a correspondence between each vertex and or , and also between each edge and or . The mentioned and can be the same for V and for E respectively. Thus we obtain an object, which is called an *-plafal and is denoted by or *, where i is a number of graph’s vertices, j is a number of graph’s edges. Generally, is called a vertex of the *-plafal and is denoted by ; is called an edge of the *-plafal and is denoted by . By we denote a collection of vertices, by we denote a collection of edges. Between and , which are connected by , there is not necessarily a logical relation. Finally, or , where is a collection of and is a collection of .
Notation
We claim that and .
is a collection of plafales.
is a collection of simple graphs as supports of .
is a collection of *-plafales.
is a collection of simple graphs as supports of .
Definition 2.1.
Labeled plafal is a type of the plafal, where all or some of vertices and/or edges are enumerated. We have , here and ; , here and ; are substitutions3. By we denote a labeled plafal, k is a quantity of enumerated vertices; l is a quantity of enumerated edges. In the case of , the plafal does not contain enumerated vertices4. In the case of , the plafal does not contain enumerated edges5. In the case of , we claim that . By τ we denote a vertex with assigned number (), by ς we denote an edge with assigned number ().
Definition 2.1 is performed for the *-plafal.
In fact, and *. Let us remark that a graph labeling is a type of such that . Evidently, we can use the following configuration . Note that τ does not necessarily coincide with a number of a graph labeling.
The illustrations of plafales and graphs are given for the reader’s perception.
Figure 1.
. Vertices: (for three vertices), the category of small sets and small multirelations. Edges: the category of sets, the set of real numbers, the set of rational numbers, . Three vertices are enumerated, one edge is enumerated. *. Vertices: (for two vertices), -category. Edges: ∞-groupoid, (for two edges). One vertex is enumerated, one edge is enumerated.
Figure 1.
. Vertices: (for three vertices), the category of small sets and small multirelations. Edges: the category of sets, the set of real numbers, the set of rational numbers, . Three vertices are enumerated, one edge is enumerated. *. Vertices: (for two vertices), -category. Edges: ∞-groupoid, (for two edges). One vertex is enumerated, one edge is enumerated.

Let us give an example in cryptography [7,10]. For a byte we get configurations: ς (for eight edges) and (for eight vertices).
Figure 2.
. Eight edges are enumerated. The plafal does not contain enumerated vertices.

Management systems
The correspondence between each vertex and (as abovementioned) is called a v-camoufleur and is denoted by . The correspondence between each edge and (as abovementioned) is called an e-camoufleur and is denoted by . By we denote a collection of camoufleurs such that , here is a collection of v-camoufleurs and is a collection of e-camoufleurs. The correspondence between each vertex and (as mentioned earlier) is said to be an -camoufleur and is denoted by . The correspondence between each edge and (as noted above) is said to be an -camoufleur and is denoted by . By we denote a collection of *-camoufleurs such that
Claim 2.2.
are categories.
Proof.
Let us show for . , , , . □
Definition 2.3.
The correspondence between each vertex and , which is changing over time, is called a dynamical v-camoufleur and is denoted by . The correspondence between each edge and , which is changing over time, is called a dynamical e-camoufleur and is denoted by . We have the following systems
Each of () has a unique time interval of changes. Let us remark that we may consider () as () in the case of .
Definition 2.3 is performed for the *-plafal. By we denote a collection of dynamical camoufleurs such that , here is called a flickering plafal. By we denote a collection of dynamical *-camoufleurs such that , here is said to be a flickering *-plafal.
Figure 3.
Management systems.

Remark 1.
*-plafales and their properties will be the object of another paper.
3. The Category of Plafales and Operations
Definition 3.1.
A plafal morphism is a tuple of maps’s collections such that
(1) , f is a graph morphism (an abstract simplicial map);
(2) : and .
Note that (2) is performed in accordance with (1).
The example is given in Figure 4.
Claim 3.2.
Plafales and plafal morphisms form the category Plafales, together with the componentwise compositions and identities . The proof is left to the reader.
Figure 4.
Condition 1. The image of under the strict homomorphism is . Condition 2. U is a functor; g is a homomorphism of groups.
Figure 4.
Condition 1. The image of under the strict homomorphism is . Condition 2. U is a functor; g is a homomorphism of groups.

Remark 2.
We may consider as a collection of .
Definition 3.3.
is called an empty plafal and is denoted by , here is the empty graph (the initial object in the categories of simple graphs (SimpGph)).
Claim 3.4.
In Plafales, there’re no initial and terminal objects.
Proof.
Initial. Omitted. Terminal. In SimpGph, there’s no terminal object. □
Definition 3.5.
A product of two plafales is defined by the graph product and the following condition holds:
(i) and .
Notice that (i) is realized in accordance with ∏.
Definition 3.6.
A coproduct of two plafales is defined by the graph coproduct and the following condition holds:
(i) in the general case, is a coproduct of categories.
Let us remark that (i) is performed in accordance with ∐.
Claim 3.7.
InPlafales, the (co)-product of any two plafales does not always exist.
Proof.
It is sufficient to consider . □
Corollary 3.8.
Plafalesis not a (quasi)-topos. The proof is streightforward.
Agreement. Moreover, we will refer a mathematical entity as an object.
3.1. Basic Operations
Elementary operations
1. Vertex deletion . 2. Edge deletion . 3. Edge addition .
Figure 5.
Elementary operations.

Advanced operations
Let us introduce the following notation. is a plafal with assigned number. In the general case, and are the components of and respectively. Let us remark that and are not the entities with the specified numbers.
In definitions 3.9 – 3.14, we will use . In definitions 3.9 – 3.11, conditions (i) are performed in accordance with the union of graphs . In definitions 3.12 – 3.14, conditions (i) are realized in accordance with the intersection of graphs .
Definition 3.9.
A union of plafales is defined by and the following condition holds:
(i) and .
Definition 3.10.
A docking of plafales is defined by and the following condition holds:
(i) and .
Definition 3.11.
A docking• of plafales is defined by and the following condition holds:
Definition 3.12.
An intersection of plafales is defined by and the following condition holds:
(i) and .
Definition 3.13.
A merger of plafales is defined by and the following condition holds:
(i) and .
Definition 3.14.
A merger• of plafales is defined by and the following condition holds:
(i) Condition (i) of definition 3.12 is performed for common vertices and for common edges; condition (i) of definition 3.13 is realized for common vertices and for common edges.
Agreement8. In definitions 3.10, 3.13, in the case of the chain of operations , and taking into account permutations for , we get For the same reason, this is performed for .
On the other hand, definitions 3.9 – 3.14 can be formulated in the following equivalent form: in general, .
Figure 6.
Advanced operations.

Definition 3.15.
A product• of two plafales is defined by the graph product and the following condition holds:
(i) , -standard.
(i) is realized in accordance with ∏. The mentioned can be different.
We stress that is a particular case of .
Definition 3.16.
A decomposition of plafales is a collection of maps such that and the following conditions hold:
(i) for k-vertices, which were located at the common vertice, of k-decomposited graphs we have: corresponds to one of the above vertices (k-variations) and for a collection of remaining -vertices corresponds a collection of arbitrary -standard objects. By the same argument, this is performed for l-edges;
(ii) and remain unchanged;
where is an operation of the decomposition of graphs; here is a collection of and is a collection of for respectively.
Remark 3.
The other types of operations will be discussed in a further paper.
4. Geo-Space
Let us introduce the following concept. A geo-space is a tuple and is denoted by , where U is a universe of -standard objects such that . The objects of the following type , which will be represented in this section, are implemented in .
4.1. Geo-Plafal
Taking into account , let us provide a definition of a geometric representation of in .
Definition 4.1.
is said to be a geo-plafal and is denoted by , here is the geometric realization of in such that in accordance with .
Let us give a comment to definition 4.1. We use the metric or coherent topologies.
On the other hand, can be formulated by analogy with the concept of the plafal. For any 1-dimensional (topological) simplicial complex9 in let there be a correspondence between each vertex and -standard, and also between each edge and -standard. The mentioned and can be the same for and for . Thus we obtain an object, which is called a geo-plafal and is denoted by or , where i is a number of vertices of , j is a number of edges of . In the general case, is called a vertex of the geo-plafal and is denoted by ; is called an edge of the geo-plafal and is denoted by . By we denote a collection of vertices, by we denote a collection of edges. Between and , which are connected by , there is not necessarily a logical relation. If and , then we say that is a trivial geo-plafal and write *. In fact, , , where is a collection of and is a collection of . By we denote a collection of geo-plafales. By we denote a collection of as supports of geo-plafales. The concepts of the labeled plafal and management systems are performed for .
Definition 4.2.
A geo-plafal morphism is a tuple of maps’s collections such that
(1) , is a morphism between polyhedra;
(2) : and .
Note that (2) is realized in accordance with (1).
Claim 4.3.
Geo-plafales and geo-plafal morphisms form the category Geo-Plafales, together with the componentwise compositions and identities . The proof is left to the reader.
Definition 4.4.
A product of two geo-plafales is defined by the product of polyhedra and the following condition holds:
(i) , .
Notice that (i) is realized in accordance with ∏.
Definition 4.5.
A coproduct of two geo-plafales is defined by the disjoint union of polyhedra and the following condition holds:
(i) in the general case, is a coproduct of categories.
Let us remark that (i) is performed in accordance with ∐.
Claim 4.6.
In Geo-plafales, there’re no initial and terminal objects. The (co)-product of any two geo-plafales does not always exist. Geo-plafales is not a (quasi)-topos. The proof is similar to the proofs in the section 3.
It is easily proved that such that and is a collection of identity functors, here SCpx is the category of abstract simplicial complexes, Top is the category of topological spaces. Note that advanced operations are performed for geo-plafales. The reader will have no difficulty in showing that , where is a 1-dimensional cellular complex.
4.2. Point
We begin with some notation for . is a limit point; is a collection of limit points.
Definition 4.7.
is a limit point in and is denoted by such that there is a correspondence between and . is a collection of limit points in .
If (a singleton in ), then we say that is a trivial point and write *. The concept of the management system is realized for .
Definition 4.8.
A morphism is a tuple of maps’s collections such that
(1) ;
(2) .
Note that (2) is performed in accordance with (1).
Claim 4.9.
and morphisms form the category PFpl.
Proof.
. We get the following commutative diagrams:

□
Remark 4. The concept of with isolated points and the concept of a flickering point, as a superposition of limit and isolated points, will be discussed elsewhere.
4.3. Manifold
Let us introduce the following notation for . M is a topological manifold; is a collection of manifolds.
Definition 4.10.
is a manifold in and is denoted by such that there is a correspondence between M (as a whole object) and . is a collection of manifolds in .
If (an object of ), then we say that is a trivial manifold and write *; here is the category of topological manifolds. The concept of the management system is realized for .
Remark 5. The concept of (open) cover of M (including the relationship with (pre)-sheaf) and a collection of objects, which corresponds to , will be the object of another paper.
Definition 4.11.
A morphism is a tuple of maps’s collections such that
(1) , is a morphism between topological manifolds;
(2) .
Notice that (2) is realized in accordance with (1).
Claim 4.12.
and morphisms Υ form the category PFM. Omitted.
Definitions 4.4, 4.5 (in terms of the product manifold and the disjoint union of topological manifolds) and results of claim 4.6 are performed for .
4.4. Dynamical System
Let us summarize and use the results of [13,14]. is a dynamical system and is denoted by d such that 10 undergoes homeomorphic transformations, here G is a topological group, is a collection of identity functors, results of advanced operations and management systems of subsections 4.1 – 4.3.
Definition 4.13.
A homomorphism d is a tuple of maps’s collections such that
(1) , is a homomorphism between dynamical systems;
(2) is a collection of maps.
Let us remark that (2) is realized in accordance with (1).
Figure 7.
Dynamical system.

5. p = np (with Pre-Prepared Tape)
The proof of the equality of complexity classes P and NP will be given in a constructive way using the apparatus of the constructive theory of serendipity approximations (CTSA)11 [4,15–24].
Remark 6. The total volume of CTSA is about 1000 papers (they can be traced evolutionarily by the indicated references).
In the general case, by S we denote an instance of an NP-complete problem. Using the deterministic machine, C is a type of S with answer “Yes” after the checking, otherwise is . The implementation model will be described after theorem 5.1. We will operate with a plane in . By we denote this topological subspace.
Theorem 5.1.
Based on the theory of plafales, there exists an algorithm that allows to check all instances of an NP-complete problem12 in polynomial time.
Proof.
1st stage. Computational template (CT). Let us consider the following labeled geo-plafal: , where SFE is a serendipity finite element (square: ) on N vertices (nodes)13. Specified vertices are evenly spaced on the boundary of SFE () by the rule
For we have the following i, here is a linear combination such that , , where t is time; and .
2nd stage. Relationship between and basis function (BF)14 . Without loss of generality, let us consider the word over a given alphabet into a representation over the alphabet . Then to each corresponds a unique “weight” ; however , G is the area of D (), where N is a quantity of instances of an NP-complete problem. Hence to each corresponds a unique collection of the basis functions (UCBF) in the CTSA. A relationship between the word and UCBF is structurally shown15.
3rd stage. The analysis of the field function (FF)16. Let us configure the CT. Without loss of generality, . So, i.
We will operate with the non-standard Dirichlet boundary value problem [4]: such that Let us comment. For C we get , otherwise is (see Figure 9).
Taking into account the field function and , let us provide the claim, which is a generalization of the results of Ph. D. thesis [19].
Claim 5.2.
For SFE on N vertices the condition of invariant of the field function (stability of the field function with respect to the basis function) is the following
Proof.
For SFE on 8 nodes the above condition is [4,19]. Let us consider the BF of SFE on N nodes in the following representation such that Let us show the rule of arrangement of the number of nodes: (see Figure 10). In the case of , b nodes are spaced on b sides of SFE.
is a collection of the basis functions of SFE on 8 nodes [4,17,22]. Therefore, , , , , , , . Let us show one of the collections of the basis functions for SFE·8.
Let us introduce the following system.
Using , we have . Let us remark that , , , .
Taking into account the above condition for SFE·8 and the properties of the BF
we get and in accordance with coordinates of in we have . Our goal is that the choice of the basis functions is insignificant. So, the expected value of difference of two field functions with different collections of the basis functions is equal to zero. To do that, let us show for the first equation of . and , then , where is a quantity of nodes on the side of SFE (see ).
Let us show for . , here are coordinates in . Thus we obtain . □
Remark 7.
There is an additional condition of symmetry of boundary values in some nodes for SFE·12 with n-parametric interpolation () and SFE·16 [19].
Further, we will use the results of Stepanets’ school17. Let us provide the results of [26]. Let be a set of all sequences of nonnegative numbers such that . Let r be a positive number and is a set of all nonincreasing sequences of positive numbers such that . In the case of , we have the following condition: . Denote by a collection of n different integers and for any and , set
and
(i) Let and . Then such that
is determined by
The exact upper bound is realized by the sequence from such that
(ii) Let and . Then is performed the following equality
here is the biggest natural number such that
The exact upper bound is realized by the sequence from such that
Note. Since solutions of these extremal problems may be of an independent interest, in the paper [26], the authors propose a new method of finding these solutions, which leads to the required result by essentially shorter and more transparent way.
Let us combine all of the above into the following provisions. It is easily shown that the conditions of [26] can be implemented for the field function . Indeed, and it is clear that in the case of . This means that the results of [26] provide an effective tool for the analysis of the field function18. Notice that the above results give an opportunity to make the estimate for (word length).
Ideology of P = NP. Due to checking the first M instances (see 1st stage: configuration of nodes) with total computational complexity of , we can identify instances without checking them19, here M is polynomially bounded. Agreement. Without loss of generality it can be assumed that a functional type of is not principled; all required are defined at time . Note that this configuration is an example of the soft mathematical modeling [25].
Let us implement the results of claim 5.2. We can assume without loss of generality that , where is a stabilization function.
Claim 5.3.
The value of the field function at the barycentre20 equals , here , see (i).
Proof.
It is easily shown that , where . Taking into account , by induction, we obtain the statement. □
Corollary 5.4.
We get , and equals , here , see (ii). The proof is omitted.
Remark 8.
Claim 5.3 links two scientific schools: CTSA and Stepanets’ school.
Using claim 5.3, corollary 5.4 and the results of the Bogolyubov principle of the decay of correlations for an infinite three-dimensional systems [27] for field function (see Figure 10), we have the following system for determination of .
Let us comment. (4) is the initial-value problem of the BBGKY hierarchy21. Taking into account , for operators (which is defined by the Poisson bracket of free particles with boundary conditions on ) and (in the case of ) we get
Each particle is characterized by the phase coordinates
for impulses : Also for (4) we take into account s-particles correlation functions [27], so
The chaos condition for s-particles correlation functions is as follows [27]:
Note that (5.4) can be obtained on the basis of the solutions of Liouville’s equations.
Taking into account and (5.1) – (5.4), is a phase space: each z-axis at the node is a particle of unit mass and diameter such that and . This implies that, such that (taking into account ) and the number of r is polynomially bounded.
Remark 9. For a metrizable space the following condition holds: existence of the space of sequences of integrable translation-invariant functions [27].
The implementation model. 1. Deterministic Turing machine (DTM). Using the DTM with polynomial memory, we operate with pre-prepared tape (see 2nd stage). Total computational complexity of the analysis of the field function (see 3rd stage) is checking the first M instances with total computational complexity of (see ideology of P = NP), checking with total computational complexity of and analysis of with total computational complexity of . Thus we have leveled the surplus of instances and P = NP is performed with pre-prepared tape. 2. Quantum Turing machine (QTM) and DTM. Using the QTM, we perform the above tape [28].
Proposition 5.5.
Using the QTM, theorem 5.1 is performed for BQP = NP.
Remark 10. For proposition 5.5: is a vector in Hilbert space (see 1st stage).
5.1. Appendix
Let us give a strengthening of the results [26] in the case of .
Let be a set of all sequences of real numbers such that
and . Let also N be a fixed positive integer and be a set of all nonincreasing sequences of nonnegative numbers such that .
Denote by a collection of n different integers and for any and , set
and
Lemma 5.6.
Let . Then for any
In this case, the exact upper bound on the right-hand side of the relation (5.6) is realized by the sequence such that
Proof.
Let be a set of all sequences such that . Then
Indeed, let . We construct a sequence such that .
Step 1. If , then represent the number in the form , where . Consider the sequence such that
Since , we have , , and . If , then we set .
Step 2. If , we represent the number in the form , where . Consider the sequence such that
Similarly, we have , , and . If , then we set .
Step N. Continuing this procedure, at Nth step we finally construct the sequence such that , and . Setting we see that it satisfies all the necessary relations.
By virtue of (5.5), for any sequence we have
To finish the proof it is sufficient to make sure that the sequence of the form (5.7) belongs to the set and
□
6. General Comments
Section 2.
1. Let us comment an informal moment for a visual perception. is a “sandwich-structure”: is a support and is a superstructure over the support.
2. Labeled plafal. Generally, we use the index collection in an alternative form with due regard for , here .
Section 4.
means that a universe of -standard objects is located outside of . Let us provide a visual perception by analogy in computer sciense. is a directory and U is a collection of external files.
Section 5.
Historical background. Dual role of the basis functions of serendipity finite elements is proved by O. Zienkiewicz (1968). His group constructed a biquadratic basis (SFE·8), but Zienkiewicz’s paradox is formed: in some nodes exist negative loads (unnatural spectrum). In 1982 Khomchenko constructed a 13-parametric bicubic basis (SFE·12) with positive loads [20], [21], thus Zienkiewicz’s paradox was solved. Methods of constructing alternative (physically correct) bases are presented in [16].
Perspective. Plafal (*-plafal) complex and plafal (*-plafal) cell complex are generalizations of the plafal (*-plafal), and this will be the object of another paper. We will give a short description. For any abstract simplicial complex (n-dimensional cell complex) let there be a correspondence between each face (k-skeleton) and -standard ( respectively).
Acknowledgments
Mathematics: A. N. Khomchenko (D. Sc., Petro Mohyla Black Sea National University), V. V. Lyubashenko (D. Sc., Institute of Mathematics of the NAS of Ukraine), A. A. Novikov (Ph. D., Novikov Labs), O. V. Rybak (Ph. D., Kyiv Polytechnic Institute), A. L. Shydlich (D. Sc., Institute of Mathematics of the NAS of Ukraine). Cryptography: L. V. Kovalchuk (D. Sc., Kyiv Polytechnic Institute). Thank you for your critical comments and consultations. Personal participation: O. Borisenko, D. Chibisov, A. Evseev, A. Kulyeshov, M. Malaev, J. Milej, V. Obod, A. Sinchuk, O. Topchyi, W. Topolski, R. Valiullin, M. Vialkov, Yazeed Abdulrahman. I am really grateful for your help.
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| 1 | The singular form is a plafal or a plafale. Pl: plafales. |
| 2 |
G is a 1-dimensional abstract simplicial complex that does not contain an isolated vertex. Generally, v is a vertex of , e is an edge of . V is a collection of vertices, E is a collection of edges. For G we have the following: a vertex is a singleton; an edge is an unordered pair. |
| 3 |
is a bijection iff ; is an injection iff . is a bijection iff ; is an injection iff . |
| 4 |
. |
| 5 |
. |
| 6 |
r is a quantity of common vertices. |
| 7 |
t is a quantity of common edges. |
| 8 | We use this agreement only as a recommendation. |
| 9 |
is a polyhedron that does not contain an isolated vertex. Generally, is a vertex of , is an edge of . is a collection of vertices, is a collection of edges. |
| 10 |
is a locally compact space satisfies the second axiom of countability. |
| 11 | Khomchenko A. N. is the founder of the scientific school of the constructive theory of serendipity approximations (from 1982). He solved Zienkiewicz’s paradox in a constructive form [20,21]. |
| 12 | The specialization of an NP-complete problem is not taken into consideration. |
| 13 | Serendipity finite element is a finite element that does not contain interior nodes. |
| 14 | Let us show the key properties of the basis function. and , where is the Kronecker delta, here i is a number of function and k is a number of node. |
| 15 | In fact, this relationship acts as a “lock” (hard model [25]): ↔ UCBF. |
| 16 | The field function (interpolant) makes an interpolation on the boundary of SFE and an approximation inside of SFE, is a value of the FF at a given node. |
| 17 | In the series of works, O. I. Stepanets’ and his successors study approximation properties of the spaces introduced by Stepanets’. Problems of finding exact values of n-term approximations of q-ellipsoids in the spaces considered are reduced to some extremal problems for series with terms that are determined as a product of elements of two nonnegative sequences one of which is fixed and another varies on certain set. |
| 18 | We are able to evaluate all “fluctuations” of the field function (according to all possible shifts). |
| 19 | We are able to level the specified surplus of instances. |
| 20 | Taking into account the results of Khomchenko’s school and Mbius’s problem (1827), we are able to manage the integral characteristics of the basis function at the barycentre. |
| 21 | The Bogolyubov (Bogoliubov) - Born - Green - Kirkwood - Yvon hierarchy. |
Figure 9.
The field function.

Figure 10.
Configuration of nodes.

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