The Independent Choice Logic for modeling multiple agents

under uncertainty

David Poole

Http://www.cs.ubc.ca/spider/poole

Presented by Mei Huang

Mar. 18,2005

Outline

Knowledge RepresentationICL OverviewICL SemanticsICL InfluenceDiscussion

Outline

Knowledge Representation ICL OverviewICL OverviewICL SemanticsICL InfluenceDiscussion

“a bridge between logical representation and belief networks”

Q?

Discussion

What do you think of the author’s claim that using disjunction to handle uncertainty is a stupid thing?

From the view point of representation, disjunction is not that bad, at least, it provides compact representations than ICL. E.g, “ea1v …v an” in ICL needs n expressions.

Outline

Knowledge RepresentationICL Overview ICL SemanticsICL SemanticsICL InfluenceDiscussion

Note: each item in F, i.e, each rules has an associated probability. E.g, for the first rule, the probability is P(f | c1, b1). This probability is different from the probability of a possible world.

Q?

Discussion

How to cast the student-take-course domain problem into ICL?

Choice Space C={{L1,L2,L3},{High,Normal,Easy}}

Facts F={Grade=A IQ=L3 ^ Difficulty=Easy;

Grade=B IQ=L2 ^ Difficulty=High; ……}

Give P0(L1), P0(L2), P0(L3), P0(High), P0(Normal),

P0(Easy)

Outline

Knowledge RepresentationICL OverviewICL Semantics ICL InfluenceICL InfluenceDiscussion

Q?

Discussion

Why it looks so straight forward to map a decision tree to the rules of ICL?

The logical part of ICL focuses on attributes’ values, not attributes. ICL’s Fact set F interprets CPDs of BLP or LoPRM.

Q?

How to translate this BN into ICL?

It is better to redraw the graph as 88 belief networks as follows:

……

Because ICL’s rules are defined on the value level.

Discussion

Burglary earthQuake

Alarm

B=true Q=true

A=true

are mutually exclusive

Outline

Knowledge RepresentationICL OverviewICL SemanticsICL InfluenceDiscussionDiscussion

Discussion

In the diagram in slide15, why the arrows are uni-directional? Can they be made bi-directional?

What can ICL buy us? I.e, is this explicit bridge between logic and decision theory necessary or is the gap between the two enlarged imaginarily by the author? (when we deal with decision projects, logic is usually embodied implicitly in the program)