webyrd/slpKanren

Stochastic Logic Programs (SLP) style probabilistic logic programming in miniKanren

{
  "createdAt": "2013-02-03T08:39:27Z",
  "defaultBranch": "master",
  "description": "Stochastic Logic Programs (SLP) style probabilistic logic programming in miniKanren",
  "fullName": "webyrd/slpKanren",
  "homepage": null,
  "language": "Scheme",
  "name": "slpKanren",
  "pushedAt": "2013-02-03T09:04:06Z",
  "stargazersCount": 34,
  "topics": [],
  "updatedAt": "2025-01-03T10:12:06Z",
  "url": "https://github.com/webyrd/slpKanren"
}

slpKanren

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 (run-prob and run-prob*):

(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, condp and 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 and run-prob* are identical to run and 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: print-substo and print-prob-substo.

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.