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Asked: 2026-06-14T03:14:21+00:00

Define a predicate that determines whether a matrix (square) is symmetric about the main

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Define a predicate that determines whether a matrix (square) is symmetric about the main diagonal. The predicate would read about, where Z is a matrix (square) symmetric about the main diagonal

symmetrical (Z)

The idea is to check that the rows and columns are equal, but do not know how to begin to raise the exercise …

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1 Answer

  1. Editorial Team

    good old matrix I,J indexing:

    symmetrical(M) :-
   forall(elem(M, I, J, E), elem(M, J, I, E)).

elem(M, I, J, E) :-
   nth1(I, M, R),
   nth1(J, R, E).

    test:

    ?- symmetrical([[a,b],[b,a]]).
true.

?- symmetrical([[a,b],[a,b]]).
false.

    note I wrote this before I saw @gusbro comment, but it’s exactly what he suggested…

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