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networks: Use streams for enumerating Boolean functions.

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This commit is contained in:
Sergiu Ivanov 2020-03-20 00:15:51 +01:00
parent 2c79ca3781
commit f09f24d2dd
2 changed files with 18 additions and 23 deletions
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4
networks-tests.rkt
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@ -219,7 +219,7 @@
[negation/list (table->function/list '((#t #f) (#f #t)))]) [negation/list (table->function/list '((#t #f) (#f #t)))])
(check-true (negation #f)) (check-false (negation #t)) (check-true (negation #f)) (check-false (negation #t))
(check-true (negation/list '(#f))) (check-false (negation/list '(#t)))) (check-true (negation/list '(#f))) (check-false (negation/list '(#t))))
(let ([f1 (car (enumerate-boolean-functions 1))] (let ([f1 (stream-first (enumerate-boolean-functions 1))]
[f1/list (car (enumerate-boolean-functions/list 1))]) [f1/list (stream-first (enumerate-boolean-functions/list 1))])
(check-false (f1 #f)) (check-false (f1 #t)) (check-false (f1 #f)) (check-false (f1 #t))
(check-false (f1/list '(#f))) (check-false (f1/list '(#t))))) (check-false (f1/list '(#f))) (check-false (f1/list '(#t)))))

37
networks.rkt
View file

@ -61,9 +61,9 @@
[tabulate/boolean (-> procedure-fixed-arity? (listof (listof boolean?)))] [tabulate/boolean (-> procedure-fixed-arity? (listof (listof boolean?)))]
[table->function (-> (listof (*list/c any/c any/c)) procedure?)] [table->function (-> (listof (*list/c any/c any/c)) procedure?)]
[table->function/list (-> (listof (*list/c any/c any/c)) procedure?)] [table->function/list (-> (listof (*list/c any/c any/c)) procedure?)]
[enumerate-boolean-tables (-> number? (listof (listof (*list/c any/c any/c))))] [enumerate-boolean-tables (-> number? (stream/c (listof (*list/c any/c any/c))))]
[enumerate-boolean-functions (-> number? (listof procedure?))] [enumerate-boolean-functions (-> number? (stream/c procedure?))]
[enumerate-boolean-functions/list (-> number? (listof procedure?))]) [enumerate-boolean-functions/list (-> number? (stream/c procedure?))])
;; Predicates ;; Predicates
(contract-out [variable? (-> any/c boolean?)] (contract-out [variable? (-> any/c boolean?)]
[state? (-> any/c boolean?)] [state? (-> any/c boolean?)]
@ -442,33 +442,28 @@
;;; Returns the n-th Cartesian power of the Boolean domain: {0,1}^n. ;;; Returns the n-th Cartesian power of the Boolean domain: {0,1}^n.
(define (boolean-power-n n) (apply cartesian-product (make-list n '(#f #t)))) (define (boolean-power-n n) (apply cartesian-product (make-list n '(#f #t))))
;;; Enumerates the truth tables of all Boolean functions of a given ;;; Returns the stream of the truth tables of all Boolean functions of
;;; arity. ;;; a given arity.
;;; ;;;
;;; /!\ There are 2^(2^n) Boolean functions of arity n. ;;; There are 2^(2^n) Boolean functions of arity n.
;;;
;;; TODO: Think about making this function lazy.
(define (enumerate-boolean-tables n) (define (enumerate-boolean-tables n)
(let ([inputs (boolean-power-n n)] (let ([inputs (boolean-power-n n)]
[outputs (boolean-power-n (expt 2 n))]) [outputs (boolean-power-n (expt 2 n))])
(for/list ([out outputs]) (for/stream ([out outputs])
(for/list ([in inputs] [o out]) (for/list ([in inputs] [o out])
(append in (list o)))))) (append in (list o))))))
;;; Enumerates all Boolean functions of a given arity. ;;; Returns the stream of all Boolean functions of a given arity.
;;; ;;;
;;; /!\ There are 2^(2^n) Boolean functions of arity n. ;;; There are 2^(2^n) Boolean functions of arity n.
;;;
;;; TODO: Think about making this function lazy.
(define (enumerate-boolean-functions n) (define (enumerate-boolean-functions n)
(map table->function (enumerate-boolean-tables n))) (stream-map table->function (enumerate-boolean-tables n)))
;;; Enumerates all Boolean functions of a given arity. As different ;;; Returns the stream of all Boolean functions of a given arity. As
;;; from the functions returned by enumerate-boolean-functions, the ;;; different from the functions returned by
;;; functions take lists of arguments instead of n arguments. ;;; enumerate-boolean-functions, the functions take lists of arguments
;;; instead of n arguments.
;;; ;;;
;;; /!\ There are 2^(2^n) Boolean functions of arity n. ;;; There are 2^(2^n) Boolean functions of arity n.
;;;
;;; TODO: Think about making this function lazy.
(define (enumerate-boolean-functions/list n) (define (enumerate-boolean-functions/list n)
(map table->function/list (enumerate-boolean-tables n))) (stream-map table->function/list (enumerate-boolean-tables n)))