## NP-containment for the coherence test of assessments of conditional probability: a fuzzy logical approach.(English)Zbl 1110.03012

Summary: In this paper we investigate the problem of testing the coherence of an assessment of conditional probability following a purely logical setting. In particular we prove that the coherence of an assessment of conditional probability $$\chi$$ can be characterized by means of the logical consistency of a suitable theory $$T_{\chi}$$ defined on the modal-fuzzy logic $$FP_k(R\text{Ł}_\Delta)$$ built up over the many-valued logic $$R\text{Ł}_\Delta$$. Such modal-fuzzy logic was previously introduced by the author [Lect. Notes Comput. Sci. 3571, 714–725 (2005; Zbl 1109.03018)] in order to treat conditional probability by means of a list of simple probabilities following the well-known (smart) ideas exposed by J. Y. Halpern [“Lexicographic probability, conditional probability, and nonstandard probability”, in: Proceedings of the eighth conference on theoretical aspects of rationality and knowledge, 17–30 (2001)] and by G. Coletti and R. Scozzafava [Probabilistic logic in a coherent setting. Dordrecht: Kluwer (2003; Zbl 1040.03017)]. Roughly speaking, such logic is obtained by adding to the language of $$R\text{Ł}_\Delta$$ a list of $$k$$ modalities for “probably” and axioms reflecting the properties of simple probability measures. Moreover we prove that the satisfiability problem for modal formulas of $$FP_k(R\text{Ł}_\Delta)$$ is NP-complete. Finally, as main result of this paper, we prove that the problem of establishing the coherence of rational assessments of conditional probability is NP-complete.

### MSC:

 03B48 Probability and inductive logic 03B52 Fuzzy logic; logic of vagueness 68Q17 Computational difficulty of problems (lower bounds, completeness, difficulty of approximation, etc.)

### Citations:

Zbl 1109.03018; Zbl 1040.03017
Full Text:

### References:

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