Winslett, M., Is belief revision harder than you thought?, in: Proceedings AAAI-86, Philadelphia, PA 119861 421-427. Received August 1985; revised version received July 1987  Home/Search   Document Not in Database   Summary   Related Articles   Check

....the propositions that are under consideration, called the set of believed propositions. When the belief revision system considers another one of these sets, we say that it changes its beliefs. Belief revision is an area of considerable interest, being both the subject of theoretical studies (e.g. [9, 18, 58]) and practical implementations (e.g. 4, 39, 41] Typically, a belief revision system explores alternatives makes choices, explores the consequences of its choices, and compares results obtained when using different choices. If, during this process, a contradiction is detected, the belief ....

Winslett, M., Is belief revision harder than you thought?, in: Proceedings AAAI-86, Philadelphia, PA 119861 421-427. Received August 1985; revised version received July 1987

....strategies and is based on the actions the opponents are supposed to take according to these strategies. 9 Belief revision has more recently been treated by philosophers (e.g. 49, 42, 60, 24, 22] theoretical computer scientists (e.g. 20] and artificial intelligence researchers (e.g. [14, 64, 50, 27, 15]) These groups view an agent s beliefs as a set of assertions (without probabilities) and revising beliefs involves deciding how that set of assertions should change when new information arrives. 10 3 The Negotiation Protocol Our strategic model of negotiation is a modification of Rubinstein ....

M. Winslett. Is belief revision harder than you thought? In Proceedings of AAAI-86, pages 421--427, Philadelphia, 1986.

....P 2 P red is a k ary predicate, x 1 ; x n are terms, and t 2 TC [ TV , then [t; P (x 1 ; x n ) is a wff (read as: P (x 1 ; x n ) is true at time t) 5 The new information may be inconsistent with the agent s current beliefs. We leave this for future discussion. See for example, [6,26,53,96,166,103,125,22,66,27]. 6 Our intention model is closer to Shoham [138] s Dec and Thomas et al. 152] s Comit than to Cohen s and Levesque [16] s Intend . 7 We have extended [152] to deal with the FOL case. We prefer this approach, where time can be expressed explicitly, over others where time periods cannot be ....

M. Winslett. Is belief revision harder than you thought? In Proceedings of AAAI-86, pages 421--427, Philadelphia, 1986.

....belief set (written A : x) While expansion is a well defined, unique operation, namely: A x def = Cn(A [ fxg) 2) the other two operations are problematical. An immediate criterion for them is that a belief set shall be changed minimally by an epistemic change operation (but cf. Winslett, 1986 ] However considering contraction, given a belief set B and a proposition x, in general there is no unique greatest belief set C B such that C 6 x. The problem of finding intuitively plausible change operations is approached by formulating sets of rationality postulates any epistemic ....

Marianne S. Winslett. Is Belief Revision Harder than You Thought?. Proc. AAAI-86, pp. 421--427. Philadelphia, Pa., August 1986.

.... phrasing the problem as one of revision of probability assessments, with Bayes s rule the central method (see, for example, 39, 21] Recently these studies have been complemented by detailed studies by philosophers (e.g. 36, 28, 42, 20, 14] and artificial intelligence researchers (e.g. [9, 17, 44, 6, 29, 32, 37]) of belief revision in a nonprobabilistic setting, in which one views the beliefs of an agent as a set of propositions and seeks to describe how a rational agent should change its set of believed propositions. Numerous practical systems for belief revision called reason maintenance or truth ....

M. Winslett. Is belief revision harder than you thought? In Proceedings of the Fifth National Conference on Artificial Intelligence, volume 1, pages 421--427, August 1986.

....and query it about its current knowledge. Given new information, the update problem is to define and compute the revised state of the database. Notable approaches to solving this problem have been suggested by Fagin, Ullman and Vardi [Fagin et al. 1983] Borgida [Borgida, 1985] Winslett [Winslett, 1986] and Weber [Weber, 1987] We suggest that the update should be considered as the revision operator ffi. Example: Let = fabg and = a:b. Since [f g is inconsistent, we generalize with respect to both a and b. G( res a ( res b ( a b Since G( is consistent with , we are ....

.... , we are done: the revised knowledge is G( f g f(a:b) ab)g. Given the model theoretic nature of our revision mechanism, the result of the update will be the same whether the knowledge base is presented as above, or as fa; bg or even fa; b; abg. In contrast, all four of [Fagin et al. 1983] [Winslett, 1986], Ginsberg, 1986] and [Weber, 1987] obtain f:a:bg as the revised database. They are thus less conservative , losing all the knowledge in the hypotheses set . Moreover, Ginsberg, 1986] and [Fagin et al. 1983] would report a different answer (the one produced by our mechanism) if the database ....

M. Winslett. Is belief revision harder than you thought? In Proceedings of AAAI-86, pages 421--427, 1986.

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