zmonx

22 ms·

121.
by zmonx 9y ago
It's definitely worth a look! Richard O'Keefe, one of the most highly regarded and accomplished Prolog programmers, even wrote his own Smalltalk implementation too: http://www.cs.otago.ac.nz/staffpriv/ok/
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by zmonx 9y ago
Thank you! I found the following chart useful: *) machine and assembly languages: simple syntax, simple semantics *) procedural languages: complex syntax, AST not available, many language constructs *) Smalltalk, LISP, Prolog: AST a
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by zmonx 9y ago
As to the first question: There are several reasons for this. One is rather inherent and can be understood by considering the following analogy: Java, C, and many other programming languages are like chess: There are many syntactic rules, a
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by zmonx 9y ago
Yes, I noticed. That's a very significant departure from Datalog syntax. "Learn Datalog Today", and learn something else from this tutorial!
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by zmonx 9y ago
Datalog is a declarative database query language with roots in logic programming. That's right, and even more holds: Syntactically, Datalog is a proper subset of Prolog!
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by zmonx 9y ago
The constraints I impose are sufficient to exclude such cases in multiplications: a/b is first evaluated, and if the result is 0, it is precluded from multiplications. To avoid also divisions resulting in 0, you are right: We can easil
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by zmonx 9y ago
Prolog is well worth learning for several reasons. One is practical and easy to explain: Syntactically, Prolog is a very simple language with a powerful implicit search mechanism. As one consequence, it lets you prototype ideas quickly , e
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by zmonx 9y ago
That's a neat puzzle! Here is the Prolog code I posted earlier, extended and adapted to solve such tasks: First, let us again start with a suitable operator definition , so that we can use × as an infix operator in expressions:
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by zmonx 9y ago
You are welcome! Prolog is a great investment: Once you have put in enough effort to solve practical tasks with it, it pays off big time, much like compound interest of capital.
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by zmonx 9y ago
Nice, thank you for sharing! For comparison, here is a Prolog solution for one of the mentioned puzzles, namely "an unusually difficult puzzle of this type, which is to make 2,5,6,6 total to 17". Let us start by defining suitable
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by zmonx 9y ago
Merci pour Prolog, Prof. Colmerauer, et toutes mes condoléances! rip(le_père_de_prolog).
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by zmonx 9y ago
Yes, this is easy to add, since there is a dedicated constraint called all_distinct/1 that we can use to express that a set of integers be pairwise distinct . In this concrete case, we get this by simply adding all_distinct(Ds) to the
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by zmonx 9y ago
For example, here is a Prolog version that describes the task you mention via constraints on integers: solution(Ds) :- length(Ds, 9), Ds ins 0..9, foldl(segment_divisible(Ds), Ds, 1, _). segm
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by zmonx 9y ago
Conversely, what if you really need a Prolog system or indeed any general purpose programming language, but only have an interface to a more limited solver? I find this even more constrained. As technology progresses, interfaces to other so
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by zmonx 9y ago
SWI-Prolog lacks a commercial-grade constraint solver that is sufficiently efficient for the tasks you might have tried. If you are interested in applying constraint solving for very complex combinatorial tasks, consider trying a Prolog sys
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by zmonx 9y ago
The trick for achieving efficient Prolog solutions of such tasks is to use the Prolog system's built-in features for constraint logic programming , abbreviated as CLP. Constraints automatically prune those parts of the search space
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by zmonx 9y ago
I second this. Prolog is extremely well suited for combinatorial optimization, and combinatorial tasks in general. There is also significant overlap between constraint programming and integer programming: Many tasks can be easily solved wit
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by zmonx 9y ago
See also cplint and the included example programs, using both regular Prolog and probabilistic extensions: http://cplint.lamping.unife.it/example/examples.swinb http://cplint.lamping.unife.it/example&#x
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by zmonx 9y ago
Very nice, thank you for sharing! For comparison, here are Prolog solutions for these tasks. The first building block is a relation between a list, one of its elements, and the list of remaining elements: list_element_rest([E|Ls],
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by zmonx 9y ago
Regarding the strength of different solvers: The solution I posted is just one out of many possible constraint-based formulations of Sudoku, using one particular domain and one particular solver implementation. In this concrete case, I have
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by zmonx 9y ago
In the solution of this exercise, 4 example puzzles are given. Here is the first one: knuth(a, [[1,_,_,_,_,6,_,8,_], [5,_,8,7,2,1,4,_,6], [_,6,_,3,8,_,2,_,1], [8,4,_,_,_,3,_,_,5],
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by zmonx 9y ago
One of the most important and characteristic aspects of constraint programming is alluded to in the following part of your quote (emphasis mine): "involves some attempt to further reduce the feasible set associated with the node by a
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by zmonx 9y ago
When you say "all open pieces have at least 2 possible values", how can the solution be unique ? Surely for each piece, some values are not admissible, otherwise this would be a contradiction. Sufficiently strong pruning could
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by zmonx 9y ago
To see what I mean, please consider the Prolog program for solving Sudoku puzzles that is shown in this article, and try the following query: | ?- sudoku(X, Y). This is called the most general query , since all arguments are fresh
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by zmonx 9y ago
I agree, with only one small additional remark: In general, a programmable search strategy sacrifices termination guarantees for more generality. That's a completely defensible approach of course, and not an argument against this pat
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by zmonx 9y ago
I do not dispute your point. However, the main issue is that the worst case complexity of this Prolog quicksort, whether in place or not, is already only polynomial , in contrast to the O(n!) permutation sort given in the article, and only
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by zmonx 9y ago
I have two comments about the Prolog code: First, the article claims: "the sudoku solver above does a brute force search", but that is specifically not the case. In fact, quite the opposite holds: The Prolog Sudoku formulation
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by zmonx 9y ago
I regard miniKanren, Racklog, core.logic, and many other Prolog-style implementations and embeddings of logic programming as extremely valuable and useful contributions that are both of academic and practical importance. They also serve the
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by zmonx 9y ago
I agree completely that SAT solvers and constraint solvers are a great choice for this. However, SAT solvers and constraint solvers blend in naturally and in fact even ship with many Prolog implementations! Thus, you can have the best of
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by zmonx 9y ago
Definitely! Prolog is extremely well suited for solving such tasks. For example, one of the most highly rated Prolog question on Stackoverflow is about a related task involving Tennis match scheduling : http://stackoverflow.com&

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