- Mail actions: [ respond to this message ] [ mail a new topic ]
- Contemporary messages sorted: [ by date ] [ by thread ] [ by subject ] [ by author ] [ by messages with attachments ]

From: Panagiotis Stamatopoulos <takis_at_...90...>

Date: Wed, 1 Apr 2020 12:34:10 +0300

Date: Wed, 1 Apr 2020 12:34:10 +0300

Thank you very much for your reply, Joachim! Actually, the origin of my question is a puzzle I was trying to solve: https://alexis.lindaikejisblog.com/photos/shares/5d56b650ce177.jpg I wanted to stick to IC, as I intended to use it for a course I teach. In addition, I wanted to get the answer just by propagation, without any labeling, as the puzzle can be solved just by logical inferences. Following your suggestion to use the reified form of #::, I ended with the program that follows. Do you believe that there could be a better solution, as far as readability is concerned (and advertisement of the advantages of CLP)? Anyway, this program works fine. Thank you very much, again. Takis ------------------------------------------------------------------------- :- lib(ic). code(X1, X2, X3) :- [X1, X2, X3] #:: 0..9, corcor(X1, X2, X3, 6, 8, 2, 1), corwro(X1, X2, X3, 6, 1, 4, 1), corwro(X1, X2, X3, 2, 0, 6, 2), corcor(X1, X2, X3, 7, 3, 8, 0), corwro(X1, X2, X3, 7, 3, 8, 0), corwro(X1, X2, X3, 7, 8, 0, 1). /* corcor/7: N is the number of correct and well placed * digits of code X1/X2/X3 compared to N1/N2/N3 */ corcor(X1, X2, X3, N1, N2, N3, N) :- #::(X1, N1, B1), #::(X2, N2, B2), #::(X3, N3, B3), N #= B1 + B2 + B3. /* corwro/7: N is the number of correct but wrongly placed * digits of code X1/X2/X3 compared to N1/N2/N3 */ corwro(X1, X2, X3, N1, N2, N3, N) :- #::(X1, [N2, N3], B1), #::(X2, [N1, N3], B2), #::(X3, [N1, N2], B3), N #= B1 + B2 + B3. ------------------------------------------------------------------------- On 01-Apr-20 11:20 AM, Joachim Schimpf wrote: > On 31/03/2020 19:22, Panagiotis Stamatopoulos wrote: >> Hello All, >> >> I hope you are healthy and safe. May I ask a (maybe trivial) question >> in the context of the IC library? Why the query >> >> ?- X #:: [1, 3], B #= (X #= 2). >> X = X{[1, 3]} >> B = B{[0, 1]} >> There is 1 delayed goal. >> >> does not enforce Β to be equal to 0? > > > IC's arithmetic equality and inequality constraints generally > enforce bounds-consistency, that's why the hole in the domain > of X is not taken into account. > > On could argue that for simple cases like X #= Y+Const stronger > domain-consistency should be enforced, this is the reason for > having http://eclipseclp.org/doc/bips/lib/ic/ac_eq-3.html . > Unfortunately, a reified version of ac_eq/3 is missing! > > If, as in your example, the equation contains only one variable, > you could use the reified form of #::, i.e. > > ?- X #:: [1, 3], #::(X, 2, B). > X = X{[1, 3]} > B = 0 > > > By the way, lib(gfd) also does what you expect: > > ?- lib(gfd). > > ?- X #:: [1, 3], B #= (X #= 2). > X = X{[1, 3]} > B = 0 > > > Cheers, > Joachim > > > _______________________________________________ > ECLiPSe-CLP-Users mailing list > ECLiPSe-CLP-Users_at_lists.sourceforge.net > https://lists.sourceforge.net/lists/listinfo/eclipse-clp-usersReceived on Wed Apr 01 2020 - 10:46:31 CEST

*
This archive was generated by hypermail 2.3.0
: Wed Sep 25 2024 - 15:13:21 CEST
*