Power set: Difference between revisions
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m →Logical (cut-free) Definition: remove redundant comment |
→Logical (cut-free) Definition: clarify meaning of efficiency |
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The predicate subseq(X,Y) is true if and only if the list X is a subsequence of the list Y. |
The predicate subseq(X,Y) is true if and only if the list X is a subsequence of the list Y. |
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The |
The definitions here are elementary, logical (cut-free), and efficient (within the class of comparably generic implementations). |
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<lang Prolog> |
<lang Prolog>powerset(X,Y) :- bagof( S, subseq(S,X), Y). |
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powerset(X,Y) :- bagof( S, subseq(S,X), Y). |
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subseq( [], []). |
subseq( [], []). |
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</lang> |
</lang> |
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Output : |
Output : |
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| ⚫ | |||
<pre> |
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X = [[], [1], [1, 2], [1, 2, 3], [1, 3], [2], [2, 3], [3]]. |
X = [[], [1], [1, 2], [1, 2, 3], [1, 3], [2], [2, 3], [3]]. |
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</pre> |
</pre> |
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