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@ -15,8 +15,8 @@
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(let loop ([argss argss][acc empty])
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(if (null? argss)
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(yield (reverse acc))
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(for ([arg (in-list (car argss))])
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(loop (cdr argss) (cons arg acc))))))))
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(for ([arg (car argss)])
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(loop (cdr argss) (cons arg acc))))))))
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(struct csp (vars constraints [assignments #:auto] [checks #:auto])
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#:mutable #:transparent #:auto-value 0)
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@ -33,7 +33,7 @@
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(raise-argument-error 'constraint-proc "csp" prob))
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;; apply proc in many-to-many style
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(for/and ([args (in-cartesian (map (λ (name) (find-domain prob name)) (constraint-names const)))])
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(apply (constraint-proc const) args))))
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(apply (constraint-proc const) args))))
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(define name? symbol?)
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@ -74,15 +74,15 @@
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((csp? (or/c (listof name?) procedure?)) ((or/c (listof any/c) procedure?)) . ->* . void?)
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(for/fold ([vrs (vars prob)]
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#:result (set-csp-vars! prob vrs))
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([name (in-list (if (procedure? names-or-procedure)
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(names-or-procedure)
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names-or-procedure))])
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([name (in-list (match names-or-procedure
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[(? procedure? proc) (proc)]
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[names names]))])
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(when (memq name (map var-name vrs))
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(raise-argument-error 'add-vars! "var that doesn't already exist" name))
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(append vrs (list (var name
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(if (procedure? vals-or-procedure)
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(vals-or-procedure)
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vals-or-procedure))))))
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(if (procedure? vals-or-procedure)
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(vals-or-procedure)
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vals-or-procedure))))))
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(define/contract (add-var! prob name [vals-or-procedure empty])
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((csp? name?) ((or/c (listof any/c) procedure?)) . ->* . void?)
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@ -92,11 +92,11 @@
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((csp? procedure? (listof (listof name?))) ((or/c #false name?)) . ->* . void?)
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(set-csp-constraints! prob (append (constraints prob)
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(for/list ([names (in-list namess)])
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(for ([name (in-list names)])
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(check-name-in-csp! 'add-constraints! prob name))
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(make-constraint names (if proc-name
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(procedure-rename proc proc-name)
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proc))))))
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(for ([name (in-list names)])
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(check-name-in-csp! 'add-constraints! prob name))
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(make-constraint names (if proc-name
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(procedure-rename proc proc-name)
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proc))))))
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(define/contract (add-pairwise-constraint! prob proc var-names [proc-name #false])
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((csp? procedure? (listof name?)) (name?) . ->* . void?)
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@ -132,7 +132,7 @@
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(check-name-in-csp! 'find-var prob name)
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(for/first ([vr (in-vars prob)]
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#:when (eq? name (var-name vr)))
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vr))
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vr))
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(define/contract (find-domain prob name)
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(csp? name? . -> . (listof any/c))
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@ -145,7 +145,7 @@
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(csp? name? . -> . any/c)
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(for/or ([vr (in-vars prob)]
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#:when (assigned-var? vr))
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(eq? name (var-name vr))))
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(eq? name (var-name vr))))
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(define/contract (reduce-function-arity proc pattern)
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(procedure? (listof any/c) . -> . procedure?)
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@ -177,20 +177,20 @@
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(ormap assigned? (constraint-names constraint)))
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(make-csp (vars prob)
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(for/list ([const (in-constraints prob)])
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(cond
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;; no point reducing 2-arity functions because they will be consumed by forward checking
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[(and (or (not minimum-arity) (<= minimum-arity (constraint-arity const)))
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(partially-assigned? const))
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(match-define (constraint cnames proc) const)
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;; pattern is mix of values and boxed symbols (indicating variables to persist)
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;; use boxes here as cheap way to distinguish id symbols from value symbols
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(define reduce-arity-pattern (for/list ([cname (in-list cnames)])
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(if (assigned? cname)
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(first (find-domain prob cname))
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(box cname))))
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(constraint (filter-not assigned? cnames)
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(reduce-function-arity proc reduce-arity-pattern))]
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[else const]))))
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(cond
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;; no point reducing 2-arity functions because they will be consumed by forward checking
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[(and (or (not minimum-arity) (<= minimum-arity (constraint-arity const)))
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(partially-assigned? const))
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(match-define (constraint cnames proc) const)
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;; pattern is mix of values and boxed symbols (indicating variables to persist)
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;; use boxes here as cheap way to distinguish id symbols from value symbols
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(define reduce-arity-pattern (for/list ([cname (in-list cnames)])
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(if (assigned? cname)
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(first (find-domain prob cname))
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(box cname))))
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(constraint (filter-not assigned? cnames)
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(reduce-function-arity proc reduce-arity-pattern))]
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[else const]))))
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(define nassns 0)
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@ -200,14 +200,18 @@
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(define (reset-nfcs!) (set! nfchecks 0))
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(define nchecks 0)
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(define (reset-nchecks!) (set! nchecks 0))
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(define/contract (assign-val prob name val)
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(csp? name? any/c . -> . csp?)
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(when-debug (set! nassns (add1 nassns)))
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(make-csp
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(for/list ([vr (vars prob)])
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(if (eq? name (var-name vr))
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(assigned-var name (list val))
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vr))
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(for/list ([vr (in-vars prob)])
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(if (eq? name (var-name vr))
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(assigned-var name (list val))
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vr))
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(constraints prob)))
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(define/contract (unassigned-vars prob)
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@ -232,7 +236,7 @@
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(csp? var? . -> . natural?)
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(for/sum ([const (in-constraints prob)]
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#:when (memq (var-name var) (constraint-names const)))
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1))
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1))
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(define/contract (domain-length var)
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(var? . -> . natural?)
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|
@ -255,7 +259,7 @@
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(random-pick (for/list ([uv (in-list mrv-uvars)]
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[degree (in-list degrees)]
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#:when (= max-degree degree))
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uv))])]))
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uv))])]))
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(define first-domain-value values)
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@ -267,8 +271,8 @@
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[cnames (in-value (constraint-names const))]
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#:when (and (= (length names) (length cnames))
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|
(for/and ([name (in-list names)])
|
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|
|
|
(memq name cnames))))
|
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|
const))
|
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|
(memq name cnames))))
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|
const))
|
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(define (two-arity? const) (= 2 (constraint-arity const)))
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|
@ -278,33 +282,33 @@
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(define/contract (forward-check prob ref-name)
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|
(csp? name? . -> . csp?)
|
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|
|
(define aval (first (find-domain prob ref-name)))
|
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|
(define (check-var v)
|
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|
|
(match v
|
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|
|
(define (check-var vr)
|
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|
|
(match vr
|
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|
|
;; don't check against assigned vars, or the reference var
|
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|
;; (which is probably assigned but maybe not)
|
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[(? (λ (x) (or (assigned-var? x) (eq? (var-name x) ref-name)))) v]
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[(? (λ (x) (or (assigned-var? x) (eq? (var-name x) ref-name)))) vr]
|
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|
[(var name vals)
|
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|
|
(match ((constraints prob) . relating-only . (list ref-name name))
|
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[(? empty?) v]
|
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|
|
[(? empty?) vr]
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|
[constraints
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|
|
(define new-vals
|
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|
|
(for/list ([val (in-list vals)]
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|
|
#:when (for/and ([const (in-list constraints)])
|
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|
|
(let ([proc (constraint-proc const)])
|
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|
|
|
(if (eq? name (first (constraint-names const)))
|
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|
|
|
(proc val aval)
|
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|
|
(proc aval val)))))
|
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|
val))
|
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|
|
|
(checked-variable name new-vals (cons ref-name (match v
|
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|
|
|
(let ([proc (constraint-proc const)])
|
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|
|
|
(if (eq? name (first (constraint-names const)))
|
|
|
|
|
(proc val aval)
|
|
|
|
|
(proc aval val)))))
|
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|
|
val))
|
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|
|
|
(checked-variable name new-vals (cons ref-name (match vr
|
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|
|
|
[(checked-variable _ _ history) history]
|
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|
|
[else null])))])]))
|
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|
|
|
(define checked-vars (map check-var (vars prob)))
|
|
|
|
|
(when-debug (set! nfchecks (+ (length checked-vars) nchecks)))
|
|
|
|
|
;; conflict-set will be empty if there are no empty domains (as we would hope)
|
|
|
|
|
(define conflict-set (for*/list ([cv (in-list checked-vars)]
|
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|
|
|
#:when (empty? (domain cv))
|
|
|
|
|
[name (in-list (history cv))])
|
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|
|
name))
|
|
|
|
|
(define conflict-set (for*/list ([cvr (in-list checked-vars)]
|
|
|
|
|
#:when (empty? (domain cvr))
|
|
|
|
|
[name (in-list (history cvr))])
|
|
|
|
|
name))
|
|
|
|
|
;; for conflict-directed backjumping it's essential to forward-check ALL vars
|
|
|
|
|
;; (even after an empty domain is generated) and combine their conflicts
|
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|
|
|
;; so we can discover the *most recent past var* that could be the culprit.
|
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|
|
@ -320,7 +324,7 @@
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|
|
(constraint-relates? const ref-name)
|
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|
|
(let ([other-name (first (remq ref-name (constraint-names const)))])
|
|
|
|
|
(singleton-var? (find-var prob other-name)))))
|
|
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|
|
const))
|
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|
|
const))
|
|
|
|
|
(make-csp checked-vars nonsingleton-constraints))
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|
|
(define/contract (constraint-checkable? const names)
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|
@ -328,7 +332,7 @@
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|
|
;; constraint is checkable if all constraint names
|
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|
|
|
;; are in target list of names.
|
|
|
|
|
(for/and ([cname (in-list (constraint-names const))])
|
|
|
|
|
(memq cname names)))
|
|
|
|
|
(memq cname names)))
|
|
|
|
|
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|
|
|
|
(define/contract (constraint-arity const)
|
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|
|
|
(constraint? . -> . natural?)
|
|
|
|
|
@ -337,8 +341,6 @@
|
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|
|
(define (singleton-var? var)
|
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|
|
(= 1 (domain-length var)))
|
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|
|
(define nchecks 0)
|
|
|
|
|
(define (reset-nchecks!) (set! nchecks 0))
|
|
|
|
|
(define/contract (check-constraints prob [mandatory-names #f] #:conflicts [conflict-count? #f])
|
|
|
|
|
((csp?) ((listof name?) #:conflicts boolean?) . ->* . (or/c csp? natural?))
|
|
|
|
|
;; this time, we're not limited to assigned variables
|
|
|
|
|
@ -346,26 +348,26 @@
|
|
|
|
|
;; we also want to use "singleton" vars (that is, vars that have been reduced to a single domain value by forward checking)
|
|
|
|
|
(define singleton-varnames (for/list ([vr (in-vars prob)]
|
|
|
|
|
#:when (singleton-var? vr))
|
|
|
|
|
(var-name vr)))
|
|
|
|
|
(var-name vr)))
|
|
|
|
|
(define-values (checkable-consts other-consts)
|
|
|
|
|
(partition (λ (const) (and (constraint-checkable? const singleton-varnames)
|
|
|
|
|
(or (not mandatory-names)
|
|
|
|
|
(for/and ([name (in-list mandatory-names)])
|
|
|
|
|
(constraint-relates? const name)))))
|
|
|
|
|
(constraint-relates? const name)))))
|
|
|
|
|
(constraints prob)))
|
|
|
|
|
(cond
|
|
|
|
|
[conflict-count?
|
|
|
|
|
(define conflict-count
|
|
|
|
|
(for/sum ([constraint (in-list checkable-consts)]
|
|
|
|
|
#:unless (constraint prob))
|
|
|
|
|
1))
|
|
|
|
|
1))
|
|
|
|
|
(when-debug (set! nchecks (+ conflict-count nchecks)))
|
|
|
|
|
conflict-count]
|
|
|
|
|
[else
|
|
|
|
|
(for ([(constraint idx) (in-indexed checkable-consts)]
|
|
|
|
|
#:unless (constraint prob))
|
|
|
|
|
(when-debug (set! nchecks (+ (add1 idx) nchecks)))
|
|
|
|
|
(backtrack!))
|
|
|
|
|
(when-debug (set! nchecks (+ (add1 idx) nchecks)))
|
|
|
|
|
(backtrack!))
|
|
|
|
|
;; discard checked constraints, since they have no further reason to live
|
|
|
|
|
(make-csp (vars prob) other-consts)]))
|
|
|
|
|
|
|
|
|
|
@ -374,15 +376,15 @@
|
|
|
|
|
;; todo: why does this function slow down searches?
|
|
|
|
|
(make-csp
|
|
|
|
|
(for/list ([vr (in-vars prob)])
|
|
|
|
|
(match-define (var name vals) vr)
|
|
|
|
|
(define procs (for*/list ([const (in-constraints prob)]
|
|
|
|
|
[cnames (in-value (constraint-names const))]
|
|
|
|
|
#:when (and (= 1 (length cnames)) (eq? name (car cnames))))
|
|
|
|
|
(constraint-proc const)))
|
|
|
|
|
(var name
|
|
|
|
|
(for*/fold ([vals vals])
|
|
|
|
|
([proc (in-list procs)])
|
|
|
|
|
(filter proc vals))))
|
|
|
|
|
(match-define (var name vals) vr)
|
|
|
|
|
(define procs (for*/list ([const (in-constraints prob)]
|
|
|
|
|
[cnames (in-value (constraint-names const))]
|
|
|
|
|
#:when (and (= 1 (length cnames)) (eq? name (car cnames))))
|
|
|
|
|
(constraint-proc const)))
|
|
|
|
|
(var name
|
|
|
|
|
(for*/fold ([vals vals])
|
|
|
|
|
([proc (in-list procs)])
|
|
|
|
|
(filter proc vals))))
|
|
|
|
|
(constraints prob)))
|
|
|
|
|
|
|
|
|
|
(define/contract (backtracking-solver
|
|
|
|
|
@ -441,9 +443,9 @@
|
|
|
|
|
((csp?) (integer?) . ->* . generator?)
|
|
|
|
|
(generator ()
|
|
|
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(for ([thread-count (or (current-thread-count) 1)]) ; todo: what is ideal thread count?
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(make-min-conflcts-thread prob thread-count max-steps))
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(make-min-conflcts-thread prob thread-count max-steps))
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(for ([i (in-naturals)])
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(yield (thread-receive)))))
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(yield (thread-receive)))))
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(define/contract (optimal-stop-min proc xs)
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(procedure? (listof any/c) . -> . any/c)
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@ -451,7 +453,7 @@
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(define threshold (argmin proc sample))
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(or (for/first ([candidate (in-list candidates)]
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#:when (<= (proc candidate) threshold))
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candidate)
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candidate)
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(last candidates)))
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(define/contract (conflicted-variable-names prob)
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@ -459,7 +461,7 @@
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;; Return a list of variables in current assignment that are conflicted
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(for/list ([name (in-variable-names prob)]
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#:when (positive? (nconflicts prob name)))
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name))
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name))
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(define/contract (min-conflicts-value prob name vals)
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(csp? name? (listof any/c) . -> . any/c)
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@ -468,7 +470,7 @@
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#:cache-keys? #true))
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(for/first ([val (in-list vals-by-conflict)]
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#:unless (equal? val (first (find-domain prob name)))) ;; but change the value
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val))
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val))
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(define no-value-sig (gensym))
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@ -482,8 +484,8 @@
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(define/contract (csp->assocs prob)
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(csp? . -> . (listof (cons/c name? any/c)))
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(for/list ([vr (in-vars prob)])
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(match vr
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[(var name (list val)) (cons name val)])))
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(match vr
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[(var name (list val)) (cons name val)])))
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(define/contract (combine-csps probs)
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((listof csp?) . -> . csp?)
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@ -491,28 +493,17 @@
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(apply append (map vars probs))
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(apply append (map csp-constraints probs))))
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(define/contract (make-cartesian-generator solgens)
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((listof generator?) . -> . generator?)
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(generator ()
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(define solstreams (for/list ([solgen (in-list solgens)])
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(for/stream ([sol (in-producer solgen (void))])
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sol)))
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(let loop ([solstreams solstreams][sols empty])
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(if (null? solstreams)
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(yield (combine-csps (reverse sols)))
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(for ([sol (in-stream (car solstreams))])
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(loop (cdr solstreams) (cons sol sols)))))))
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(define/contract (extract-subcsp prob names)
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(csp? (listof name?) . -> . csp?)
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(make-csp
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(for/list ([vr (in-vars prob)]
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#:when (memq (var-name vr) names))
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vr)
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vr)
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(for/list ([const (in-constraints prob)]
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#:when (for/and ([cname (in-list (constraint-names const))])
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(memq cname names)))
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const)))
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(memq cname names)))
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const)))
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(define/contract (solve* prob
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#:finish-proc [finish-proc csp->assocs]
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@ -525,12 +516,17 @@
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(define subcsps ; decompose into independent csps. `cc` determines "connected components"
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(if (current-decompose)
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(for/list ([nodeset (in-list (cc (csp->graph prob)))])
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(extract-subcsp prob nodeset))
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(extract-subcsp prob nodeset))
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(list prob)))
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(define solgens (map solver subcsps))
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(define solstreams (for/list ([solgen (in-list solgens)])
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(for/stream ([sol (in-producer solgen (void))])
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sol)))
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(for/list ([solution (in-producer (make-cartesian-generator (map solver subcsps)) (void))]
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(for/list ([solution-pieces (in-cartesian solstreams)]
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[idx (in-range max-solutions)])
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(finish-proc solution)))
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(finish-proc (combine-csps solution-pieces))))
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(define/contract (solve prob
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#:finish-proc [finish-proc csp->assocs]
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