Logic programming

Introduction To express program in symbolic logic Also called declarative language Only the specification of desired results are stated State the form of the result rather than how a result is to be computed Logic programming is a declarative approach of writing computer programs based on Logic

Brief history 1970s AI group To specifying predicate calculus Prolog

Predicate calculus Proposition: a logical statement that is true or not true Formal logic describes proposition that allows them to be checked or validity

Logic Programming – Example Suppose we have the following sentences 1. CS student of NTHU must take the core course cs A CS student can not obtain a degree without passing the required course I am a CS student of NTHU and want to obtain a degree, should I pass cs2403?

/* Filename: ancestor.pro This program creates a small set of facts and rules on who is the ancestor of whom. The user types the desired goal interactively when the program is run.*/ /* ancestor(A, B) means A is an ancestor of B */ ancestor(bob, susan). ancestor(A, X) :- parent(A, X). ancestor(A, X) :- parent(A, C), ancestor(C, X). /* parent(P, C) means P is a parent of C */ parent(fred, sally). parent(tina, sally). parent(sally, diane). parent(sam, bill).

Logic Programming – Prolog Query Queries: ancestor(fred, sally). Yes ancestor(fred, diane). Yes ancestor(fred, bill). No

Logic Programming – Reference Book: Ralph P. Grimaldi, DISCRETE AND COMBINATORIAL MATHEMATICS, 5TH ED, Pearson Education, 2004 Ulf Nilsson and Jan Ma luszy_nski, LOGIC, PROGRAMMING AND PROLOG, 2ND ED, Ulf Nilsson and Jan Ma luszy_nski, 2000 Web: