18 and 25 Feb 2004
CS 3243 - Logical Agents
33
Proof methods
nProof methods divide into (roughly) two kinds:
nApplication of inference rules
nLegitimate (sound) generation of new sentences from
old
nProof
= a sequence of inference rule applications
Can use inference rules as operators in a standard search algorithm
Can use inference rules as operators in a standard search algorithm
nTypically require transformation of sentences into a normal form
nModel checking
ntruth table enumeration (always exponential in n)
nimproved backtracking, e.g.,
Davis--Putnam-Logemann-Loveland (DPLL)
nheuristic search in model space (sound but
incomplete)
e.g., min-conflicts like hill-climbing algorithms