1. Introduction
Starting from “An Investigation of the Laws of Thought” by Bool [
1], data analysis and decision-making are considered using the methods of formal logic and probability theory involving rational principles of judgement and reasoning. Logic formalizes the rules for deriving truthiness of the statements, and probability theory provides rigorous methods for handling uncertainty in the knowledge about the statements and events.
Combination of the concepts of uncertainty and truthiness gave a rise for the development of multivalued logic; the first version of such logic – the three valued logic – was suggested by Łukasiewicz [
2]. Later Łukasiewicz and Tarski [
3] extended this logic to the
-valued logic.
Further development of the multivalued logic resulted in probabilistic logic [
4] and fuzzy logic [
5]. After formulation of the uninorm [
6] and absorbing norm [
7], fuzzy logic forms a basis for the development of non-Bayesian decision-making and of non-probabilistic methods of handling uncertainty [
8].
In parallel to the development of multivalued logics, Lambek [
9] initiated the studies of non-commutative logics. At the beginning, these logics were developed for representation of the syntactical and grammatical structures of natural languages, and then were adopted for modeling preference relations in the decision-making processes [
10,
11]. Theoretical studies in these directions resulted in the invention of multivalued non-commutative operators [
12] and multivalued non-commutative logics algebras [
13] that allow direct consideration of the situations where truthiness depends on the order of the statements.
The attempts to use the multivalued non-commutative logics in decision-making gave a rise to two main problems: how to implement the non-commutative logical operators, and how to define the correct “level of non-commutativity” of these operators.
In the paper, we suggest the implementation of non-commutative logical operators based on the extension of the uninorm and absorbing norm [
14]. In addition to the neutral and absorbing elements, these norms are equipped with the asymmetry parameter which controls the “level of non-commutativity”. To define the value of this parameter we utilize the phenomenon of “the bias of the crowd” [
15,
16,
17] in its basic form of the perceptional bias originated by Galton [
18]. We consider the perception of weight, length and time and specify the asymmetry of the uninorm and absorbing norm by the difference between the perceived and real weights, lengths, and times.
The activity of the obtained non-commutative logical operators is illustrated by their application for decision-making in the group of mobile robots.
2. Non-commutative algebra of multi-valued logic
In this section we define the non-commutative algebra of multi-valued logic. Since it is based on the previously developed commutative algebra, we start with this algebra and then consider its non-commutative extension.
2.1. Algebra with multi-valued logical operators
Let
be the uninorm6] with the parameter
called neutral or identity element such that
is the
-norm (or multivalued
operator) and
is the
-conorm (or multivalued
operator). In addition, let
be the absorbing norm [
7] with the parameter
called absorbing element; this norm is a multivalued version of the
operator.
Usually, it is assumed that the uninorm and absorbing norm are commutative and associative and that the uninorm is transitive. The elements and play the role of unit and zero for their operators such that and , .
The uninorm
and the absorbing norm
considered as operators on the interval
form an algebra [
14,
21]
in which the uninorm
acts as a summation with the zero
and the absorbing norm
acts as a multiplication with the unit
.
If the norms
and
are commutative, then there exist the functions
and
called generator functions [
22] such that for any
For the boundary values it is assumed that the norms and act appropriate Boolean operators with respect to the values of the elements and .
For completeness, in the algebra
the inverse operations, subtraction
and division
are defined as
with obvious condition
.
If
and
for any
, then the algebra
is distributive with
for any
.
Assume that for any
the generator functions with the parameter
are equivalent
and are defined as follows
Respectively, the inverse functions are
The graphs of these functions are shown in
Figure 1.
The uninorm
and the absorbing norm
are commutative; the graphs of these norms are shown in
Figure 2.
Algebra extends Boolean algebra with conjunction and disjunction operators, and its multivalued version with -norm and -conorm , and defines the multivalued logic with logical operators and . The uninorm is associated with the multivalued and operators, and the absorbing norm is associated with the multivalued operator. In addition, it acts as an arithmetic system on the interval , where the uninorm is associated with the arithmetical weighted summation “” and absorbing norm is associated with arithmetical multiplication “”, both for real numbers from the interval .
2.2. Non-commutative extension of the algebra
The suggested definition of non-commutative version of the algebra
is based on the definition of uninorm and absorbing norm using generator functions and given by equations (2) and (3). Formally, we define the non-commutative uninorm
and absorbing norm
as follows:
with the same as above assumption about the boundary values. Similar,
with
.
In general, the operators and are non-commutative. The commutativity holds if, respectively, and . If and , then these operators are equivalent to the norms and .
The algebra
with the operators
and
is the non-commutative version of the algebra
. For arbitrary parameters this algebra is also non-distributive.
To illustrate the non-commutativity of the operators
and
assume that generator functions and their inverses are defined by the equations (7) and (8) and that
In addition, assume that the
and
are defined as follows
It means that if
, then
and
(cf. definitions of subjective false and subjective truth [
23]). The graphs of the non-commutative uninorm
and absorbing norm
with these parameters are shown in
Figure 3.
The norms
and
preserve their general form (cf. the graphs of the commutative norms in
Figure 2) but demonstrate clear dependence of the results on the order of the arguments. For example,
while
In this example, parameters
,
and
are defined by equations (15) and (16) such that
; then the preference in the operations is given to the first operand in such a sense that the result is as greater as the first operand is greater than the second operand. If the relation between the parameters is
, then the preference is opposite, and the result is as greater as the second operand is greater than the first operand. This observation is summarized in
Table 1.
In addition, by the reasons of symmetry the substitution of the parameters
and
results in the equivalences
Summarizing, in the algebra
the uninorm
and absorbing norm
are non-commutative and their results depend on the order of the operands
These norms provide the logical operations that can be used in the algorithms of decision-making with preferences [
10,
11] and for implementation of non-commutative logics [
13]. Below, we illustrate such implementation by the decision-making in the group of mobile robots.
3. Perception bias in group
Definition of exact values of the parameters , , and , , requires additional analysis of the considered situation and of the meaning of the parameters and arguments. Here we assume that the decision-making is conducted by artificial agents that can perceive certain measured data and mimic the perceptional bias observed in the groups of humans.
The studies of perception bias in groups and of the bias of the crowd in general were originated by Galton in 1907. In his paper “Vox populi” [
18], Galton presented the results of the survey about the estimated weight of the fat ox. It was found that distribution of individual estimations is not normal and that the mean value of the estimated weights differs from the real weight of the ox. Nowadays, this paper is considered as an origin of studies in the field of “the wisdom of the crowd” [
24].
Following the Galton approach, we conducted three surveys that considered the estimations of weights, lengths, and times, which are the basic physical values used in classical mechanics. However, in contrast to Galton, we used the values in the usual for ordinary people ranges –grams and kilograms for weights, centimeters and decimeters for lengths and seconds for times.
The surveys were organized as follows (the approvement of the Ariel University Ethics Commission AU-ENG-EK-20230205, Feb 5 2023). For measurements we used the following objects:
the estimations of the weights were checked using the equivalently looked boxes with the weights kg, kg and kg;
the estimations of the lengths were checked using the ropes (made from the same material) with the lengths cm, cm and cm; and
the estimations of times were checked using the sounds of Hz of the durations sec, sec and sec.
In all the cases, the not round values were chosen in order to avoid the natural tendency of the humans to round the estimations.
The participants of the surveys were the students at Ariel University and the adults with academic degrees. The number of participants in the surveys was form
to
persons, the average age is
(the youngest participant was
years old and the oldest was
years old). The results of the surveys are summarized in
Table 2.
For all considered weights the means kg, kg and kg of the estimated values are smaller than the real weights kg, kg and kg of the objects. By the -test, distributions of the weights’ estimations are not normal and the differences between the real weights and the means of the estimations are significant with significance level .
The same tendency holds for the greater lengths: the means cm and cm of the estimated values are smaller than the real lengths cm, cm of the ropes. However, for the short rope the mean estimated length cm is greater than its real length cm. For the short rope, the -test with shows that the distribution of the length estimations is normal and difference between real length and the mean of the estimations is not significant, while for the longer ropes the distributions of the length’s estimations are not normal.
For the sounds durations the tendency is opposite. For all considered durations the means
sec,
sec and
sec of estimated values are greater than the real durations
sec,
sec and
sec. However, the
-test with
shows that the distributions of the times estimations are normal and difference between real length
and the mean
of the estimations is not significant. The histograms of the estimated values are shown in
Figure 4.
Thus, for all weights and for the longer ropes the observed results coincide the Galton’s observation that the estimations are not normal, but for the short rope and for all durations the distributions of the observed results are normal. In addition, note that in contrast to Galton’s statement, the medians in the observed data also strongly differ from the real values and cannot be considered as better estimators than the means.
4. Definition of the aggregators’ parameters in algebra
Parameters of the uninorm and absorbing norm can be defined by several ways. Here we suggest one possible definition of the parameters based on the considered above perception bias. Such definition coincides with the further application of the algebra for decision-making in mobile robots, where we assume that the decision-making depends on the perceived and stored objective data with no involvement of informal valuations and judgements.
As above, we assume that for both norms equal parameters defined by equations (14)-(16). The value of the parameter based on the differences between real values of the weights, lengths and times and the means of estimated values is defined as follows.
The normalized difference between real values and the means of estimations is
It is clear that and if , then . Here we also assume that the considered values are not negative so .
The values of the normalized difference
are linearly transformed to the values of the parameter
as follows
In the decision-making processes we apply the norms
and
with the parameter
defined for the appropriate measurement – of the weights, the lengths, and the times. The examples of the uninorm and absorbing norm for estimations of the weight
kg and of the time
sec are shown in
Figure 5.
The values of the parameter change the curvature of the surface produced by the aggregations’ results that represents the biased influence of the perceived data to the decisions.
Note again that the suggested method based on the simple formulas (21) and (22) is not a unique or preferred one and can be substituted by the other. For example, in the control of mobile robots [
25] we used the extended algebra
with commutative norms
and
action on the interval
. In this case, the processing of the negative parameters and arguments was conducted on the level of generator function and its inverse without use of the formula (22) or similar.
5. Control of mobile robots in and group activity
Let us consider application of the suggested operators of the non-commutative algebra
for control of mobile robots acting in group. In the simulations, we use the previously defined construction of the robots [
25], but for the robots’ control apply the presented above non-commutative operators. As above, we consider the norms
and
with the parameters defined by equations (15) and (16).
Assume that each robot includes two active elements – the head
and the tail
, and denote by
and
the states of these elements at time
, respectively,
for all
The attraction/repulsion force between the robots are formed by four attraction/repulsion forces between the robots’ heads and tails
where
is an attraction/repulsion coefficient,
is a distance between the robots’ heads and tails located in the points with the coordinates
and
at time
, and
is a control value with the attraction/repulsion value
The scheme of the robots and attraction and repulsion is shown in
Figure 6.
Note that the function that defined the control value in equation (25) is an inverse of the transformation used in equation (22). It transforms the attraction/repulsion values to the control values .
The states
and
,
, of the active elements are updated according to the rule of the subjective Markov process [
23] as follows [
25] (
).
To illustrate the activity of the group of the robots we simulated the motion of the group of robots in the gridded square domain of the size . The distances between the robots are Euclidean, and the attraction/repulsion forces act between the neighboring robots up to the distance . The value of the attraction/repulsion coefficient is the tenth part of the domain diagonal that is .
In the simulations the robots started from the ordered configuration shown in
Figure 7. The states
and
,
of the head and tail of each robot are specified by random with respect to uniform distribution on the interval
.
Figure 8 shows the activity of the group of the robots with the operators’ parameters corresponding to the human perception errors in estimating weight
kg (see
Figure 5a).
The robots start from their positions in the nodes of the grid and with time repulse one from another. As a result, they leave the central part of the domain toward the borders.
In contrast, if the robots use the operators with the parameters corresponding to the human perception errors in estimating time
sec (see
Figure 5b), they attract each other. Activity of the group of such robots is shown in
Figure 9.
As above, the robots start from their positions in the nodes of the grid, but in contrast to previous case, they attract one another, and the group concentrates and moves as a swarm.
For comparison,
Figure 10 shows the activity of the robots with commutative operators with the parameters
representing the absence of perception bias.
In the case of commutative operators, the group does not demonstrate a certain motion tendency. However, for certain initial states and , the robots can form cliques with the average distance between them .
The simulations demonstrate that the behavior of the group of the robots depends on the parameters of the non-commutative uninorm
and absorbing norm
. For negative perception bias while the average estimation is lower than the real value, the robots repulse each other, and the group disperses (see
Figure 8). In contrast, for positive perception bias while the average estimation is higher that the real value, the robots attract each other, and the group concentrates and moves as a unit (see
Figure 9).
6. Discussion
The paper continued our previous works [
14,
25,
26] on multivalued logic algebra based on parameterized uninorm and absorbing norm and suggested the non-commutative version of such algebra.
The consideration aims two main goals. The first is to construct simple and computable implementation of non-commutative multivalued logic algebra, which can be used for decision-making under uncertainty. And the second is to form a basis for further analysis of irrational decisions and modelling the paradoxes of rationality [
27].
We demonstrated the use of the suggested algebra to control mobile robots acting in a group, where the level of non-commutativity was defined by human perceptional bias. The conducted simulations verified the possibility of formal processing of systematic errors in sensing, and of distinguishing and mimicking the biased decisions.
Further work will concentrate on the modelling and analysis of irrational decisions. It sounds true that in many cases the irrationality in the decisions is apparent and can be explained either by certain statistical errors [
28] or by non-commutativity and asymmetry of logical operations. The results of this work will allow the use of non-commutative logic both for processing the sensed data and for forming rational decisions in irrational conditions.
7. Conclusions
We suggested the implementation of non-commutative multivalued logic algebra. The “level of non-commutativity” in this algebra is controlled by the external asymmetry parameter.
The value of the asymmetry parameter we defined on the base of perception bias of humans, which was found in observations of expected values of basic physical measures – weight, length, and time.
In the experiments we considered the usual values of weights, lengths, and times. It was observed that for all weights from kg to kg and for the lengths cm and cm the estimations’ distributions are not normal, and the estimations’ means are lower than the real values of the considered measures. In contrast, for the length of cm and for all times from sec to sec the estimations’ distributions are normal, and the estimations’ means are higher than the real values of the measures.
The operators of the suggested non-commutative multivalued logic algebra were used for control of mobile robots acting in group.
In the simulations it was observed that for negative perception bias (the estimations’ mean is lower than the real value), the group disperses, and for positive perception bias (estimations’ mean is higher that the real value), the group concentrates and moves as a unit.
As a result, we obtained the implementation of non-commutative multivalued logic algebra, the tendency and the values of the perception bias for basic physical measures and the method of control of mobile robots in the group based on the implemented algebra and taking into account the differences in the perception of different types of measures.
Supplementary Materials
The following supporting information can be downloaded at the website of this paper posted on Preprints.org, Videos S1, S2 and S3.
Author Contributions
Conceptualization, E.K. and A.R.; methodology, E.K and A.N.; software, E.K.; validation, A.N. and D.R.; formal analysis, E.K. and A.R.; investigation, E.K. and A.R.; resources, D.R.; data curation, A.N.; writing—original draft preparation, E.K. and D.R.; writing—review and editing, A.N. and A.R.; supervision, A.R.; project administration, E.K. All authors have read and agreed to the published version of the manuscript.
Funding
This research received no external funding.
Data Availability Statement
Data available on request and can be received from the corresponding author.
Conflicts of Interest
The authors declare no conflict of interest.
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Figure 1.
Generator function and its inverse with .
Figure 1.
Generator function and its inverse with .
Figure 2.
Uninorm and absorbing norm with .
Figure 2.
Uninorm and absorbing norm with .
Figure 3.
Non-commutative uninorm and absorbing norm with , and .
Figure 3.
Non-commutative uninorm and absorbing norm with , and .
Figure 4.
Histograms of the estimated values: (a) the weights, (b) the lengths, and (c) the times.
Figure 4.
Histograms of the estimated values: (a) the weights, (b) the lengths, and (c) the times.
Figure 5.
Non-commutative uninorm and absorbing norm for the estimations (a) of the weight kg and (b) of the time sec.
Figure 5.
Non-commutative uninorm and absorbing norm for the estimations (a) of the weight kg and (b) of the time sec.
Figure 6.
Scheme of the robots and attraction/repulsion forces. The headings of the robots are specified by bold arrows.
Figure 6.
Scheme of the robots and attraction/repulsion forces. The headings of the robots are specified by bold arrows.
Figure 7.
Stating positions of the robots.
Figure 7.
Stating positions of the robots.
Figure 8.
Evolution of the initial configuration of the robots’ group with the operators’ parameters corresponding to the weight kg: (a) locations after two movements of each robot, ; (b) locations after five movements of each robot, ; (c) locations after ten movements of each robot, ; and locations after the hundred movements of each robot, .
Figure 8.
Evolution of the initial configuration of the robots’ group with the operators’ parameters corresponding to the weight kg: (a) locations after two movements of each robot, ; (b) locations after five movements of each robot, ; (c) locations after ten movements of each robot, ; and locations after the hundred movements of each robot, .
Figure 9.
Evolution of the initial configuration of the robots’ group with the operators’ parameters corresponding to the time sec: (a) locations after two movements of each robot, ; (b) locations after five movements of each robot, ; (c) locations after ten movements of each robot, ; and locations after the hundred movements of each robot, .
Figure 9.
Evolution of the initial configuration of the robots’ group with the operators’ parameters corresponding to the time sec: (a) locations after two movements of each robot, ; (b) locations after five movements of each robot, ; (c) locations after ten movements of each robot, ; and locations after the hundred movements of each robot, .
Figure 10.
Evolution of the initial configuration of the robots’ group with commutative operators with the parameters : (a) locations after two movements of each robot, ; (b) locations after five movements of each robot, ; (c) locations after ten movements of each robot, ; and locations after the hundred movements of each robot, .
Figure 10.
Evolution of the initial configuration of the robots’ group with commutative operators with the parameters : (a) locations after two movements of each robot, ; (b) locations after five movements of each robot, ; (c) locations after ten movements of each robot, ; and locations after the hundred movements of each robot, .
Table 1.
Dependence of the operations’ results on the relation between the parameters.
Table 1.
Dependence of the operations’ results on the relation between the parameters.
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Table 2.
Results of the surveys: real and estimated values of the weights, lengths, and times.
Table 2.
Results of the surveys: real and estimated values of the weights, lengths, and times.
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Weight [kg] |
Length [cm] |
Time [sec] |
Real values
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Mean of estimated values
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Median of estimated values
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Standard deviation
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Difference
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