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Taras Radul

Publications and source records attributed to Taras Radul.

At least 19 recordsLinked to original sources
arXiv2026

On exact capacities

We consider capacity (fuzzy measure, non-additive probability) on a compactum as a monotone cooperative normed game. We introduce topological analogues of well known class of exact games and show that these classes form subfunctors of the capacity functor which lie between known subfunctors of convex capacities and balanced capacities. It is natural to consider probability measures as elements of core of such games. We describe exact capacities as envelopes of the convex closed sets of probability measures. Using such representation we prove openness of the functor of exact capacities. We also consider strongly exact capacities and pose the problem of coincidence of these two classes.

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arXiv2026

Equilibrium for max-plus payoff

We study equilibrium concepts in non-cooperative games under uncertainty where both beliefs and mixed strategies are represented by non-additive measures (capacities). In contrast to the classical Nash framework based on additive probabilities and linear convexity, we employ capacities and max-plus integrals to model qualitative and idempotent decision criteria. Two equilibrium notions are investigated: Nash equilibrium in mixed strategies expressed by capacities, and equilibrium under uncertainty in the sense of Dow and Werlang, where players choose pure strategies but evaluate payoffs with respect to non-additive beliefs. For games with compact strategy spaces and continuous payoffs, we establish existence results for both equilibrium concepts using abstract convexity techniques and a Kakutani-type fixed point theorem.

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arXiv2025

On monotonicity of comonotonically maxitive functional

The comonotonic maxitivity property of functionals frequently appears in the characterization of fuzzy integrals based on the maximum operation. In some special cases, comonotonic maxitivity implies monotonicity of functionals. The question of whether this implication holds in general was posed by T. Radul (2023). It was shown in that paper that the implication is valid for finite compacta. In this article, we provide a negative answer to the general problem and discuss additional properties that need to be imposed to ensure the implication holds.

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arXiv2024

On the functor of comonotonically maxitive functionals

We introduce a functor of functionals which preserve maximum of comonotone functions and addition of constants. This functor is a subfunctor of the functor of order-preserving functionals and contains the idempotent measure functor as subfunctor. The main aim of this paper is to show that this functor is isomorphic to the capacity functor. We establish such isomorphism using the fuzzy max-plus integral. In fact, we can consider this result as an idempotent analogue of Riesz Theorem about a correspondence between the set of $\sigma$-additive regular Borel measures and the set of linear positively defined functionals.

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arXiv2024

On the openness of the idempotent barycenter map related to a t-norm

We demonstrate that the idempotent barycenter map, associated with a t-norm $\ast$, is open if and only if the map of max-$\ast$ convex combination is open. As a corollary, we deduce that the idempotent barycenter map is open for spaces of idempotent measures associated with any t-norm $\ast$. Nevertheless, we illustrate that the characteristics of the idempotent barycenter map, in general, depend on the specific t-norm being employed.

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arXiv2023

On idempotent convexities and idempotent barycenter maps

We consider an isomorphism between the idempotent convexity based on the maximum and the addition operations and the idempotent measure convexity on the maximum and the multiplication operations. We use this isomorphism to investigate topological properties of the barycenter map related to the maximum and the multiplication operations.

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arXiv2023

An isomorphism of idempotent monads

We consider isomorphism between the idempotent measure monad based on the maximum and the addition operations and the idempotent measure monad based on the maximum and the multiplication operations. A one of the consequences of this result is the construction of a fuzzy integral based on the maximum and the addition operation. We also investigate convexities related to these monads.

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arXiv2022

Some remarks on characterization of t-normed integrals on compacta

A characterization of t-normed integrals was obtained in \cite{CLM} for finite compacta and in \cite{Rad} for the general case. Such characterization establishes a correspondence between the space of capacities and homogeneous respect t-norm monotone normed functionals preserving the maximum operation of comonotone functions. In fact these theorems we can consider as non-additive and non-linear analogues of well-known Riesz Theorem about a correspondence between the set of $\sigma$-additive regular Borel measures and the set of linear positively defined functionals. We discuss optimality of such characterization.

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arXiv2021

On t-normed integrals with respect to possibility capacities on compacta

Riesz Theorem establishes a correspondence between the set of $\sigma$-additive regular Borel measures and the set of linear positively defined functionals. We consider an idempotent analogue of this correspondence between possibility capacities and functionals preserving the maximum operation and t-norm operation using t-normed integrals.

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arXiv2021

On balanced capacities

We consider capacity (fuzzy measure, non-additive probability) on a compactum as a monotone cooperative normed game. Then it is naturally to consider probability measures as elements of core of such game. We prove an analogue of Bondareva-Shapley theorem that non-emptiness of the core is equivalent to balancedness of the capacity. We investigate categorical properties of balanced capacities and give characterizations of some fuzzy integrals of balanced capacities.

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arXiv2020

Equilibrium under uncertainty with fuzzy payoff

This paper studies n-player games where players beliefs about their opponents behaviour are capacities (fuzzy measures, non-additive probabilities). The concept of an equilibrium under uncertainty was introduced by J.Dow and S.Werlang (1994) for two players and was extended to n-player games by J.Eichberger and D.Kelsey (2000). Expected utility (payoff function) was expressed by Choquet integral. The concept of an equilibrium under uncertainty with expected utility expressed by Sugeno integral were considered by T.Radul (2018). We consider in this paper an equilibrium with expected utility expressed by fuzzy integral generated by a continuous t-norm which is a natural generalization of Sugeno integral.

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arXiv2019

Bundle of idempotent measures

We investigate when the idempotent barycenter map restricted to the points with no-trivial fibers is a trivial bundle with the fiber Hilbert cube.

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arXiv2019

Games in possibility capacities with payoff expressed by fuzzy integral

This paper studies non-cooperative games where players are allowed to play their mixed non-additive strategies. Expected payoffs are expressed by so-called fuzzy integrals: Choquet integral, Sugeno integral and generalizations of Sugeno integral obtained by using triangular norms. We consider the existence problem of Nash equilibrium for such games. Positive results for Sugeno integral and its generalizations are obtained. However we provide some example of a game with Choquet payoffs which have no Nash equilibrium. Such example demonstrates that fuzzy integrals based on the maximum operation are more suitable for possibility capacities then Choquet integral which is based on the addition operation.

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arXiv2019

A functional representation of the capacity multiplication monad

Functional representations of the capacity monad based on the max and min operations were considered in \cite{Ra1} and \cite{Ny1}. Nykyforchyn considered in \cite{Ny2} some alternative monad structure for the possibility capacity functor based on the max and usual multiplication operations. We show that such capacity monad (which we call the capacity multiplication monad) has a functional representation, i.e. the space of capacities on a compactum $X$ can be naturally embedded (with preserving of the monad structure) in some space of functionals on $C(X,I)$. We also describe this space of functionals in terms of properties of functionals.

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