racket/collects/tests/datalog/examples/revpath.rkt
2010-06-25 22:36:12 -06:00

7 lines
169 B
Racket

#lang datalog
% path test from Chen & Warren
edge(a, b). edge(b, c). edge(c, d). edge(d, a).
path(X, Y) :- edge(X, Y).
path(X, Y) :- path(X, Z), edge(Z, Y).
path(X, Y)?