Stochastic Logic Programs (SLP) style probabilistic logic programming in miniKanren, based on Stephen Muggleton's paper, 'Stochastic Logic Programs': http://www.doc.ic.ac.uk/~shm/Papers/slp.pdf
Code by Rebecca Swords and William E. Byrd, based on core miniKanren.
slpKanren extends core miniKanren with one relational operator (
condp) and two interface operators (
(condp [prob-exp g g* ...] ...)
condp is identitical to
conde, except that the first expression in each clause must evaluate to a real number representing the probability associated with that clause. Operationally,
condp behaves identically to
conde, other than associating a probability with each successful clause. In other words,
conde produce the same answers, in the same order; however,
condp associates a probility with each answer.
(run-prob n (x) g0 g ...) (run-prob* (x) g0 g ...)
run-prob* are identical to
run*, except that the probability associated with each answer is also returned.
This implementation also includes two debugging goals, which can be used to examine the substition:
Example slpKanren program, adapted from the Muggleton paper:
;;; stochastic automaton (define sa (lambda (S) (letrec ([q0 (lambda (S) (exist (S^) (condp [0.4 (== `(a . ,S^) S) (q0 S^)] [0.6 (== `(b . ,S^) S) (q1 S^)])))] [q1 (lambda (S) (exist (S^) (condp [0.7 (== `(b . ,S^) S) (q1 S^)] [0.3 (== `(c . ,S^) S) (q2 S^)])))] [q2 (lambda (S) (== '() S))]) (q0 S))))
and associated test cases:
(test "sa-1" (run-prob 10 (q) (sa q)) '(((b c) . 0.18) ((b b c) . 0.126) ((a b c) . 0.072) ((b b b c) . 0.08819999999999999) ((b b b b c) . 0.06173999999999999) ((a b b c) . 0.0504) ((b b b b b c) . 0.043217999999999986) ((b b b b b b c) . 0.03025259999999999) ((a a b c) . 0.0288) ((a b b b c) . 0.03528)))
(test "sa-2" (run-prob 1 (q) (== '(a b b c) q) (sa q)) `(((a b b c) . ,(* 0.4 0.6 0.7 0.3))))
All Scheme code tested under Petite Chez Scheme Version 8.4.