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79 lines
1.6 KiB
Mathematica
79 lines
1.6 KiB
Mathematica
%---------------------------------------------------------------------------%
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% vim: ts=4 sw=4 et ft=mercury
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%---------------------------------------------------------------------------%
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%
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% This is a test for whether multiple coups (change of leaders)
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% are correctly handled.
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:- module coup3.
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:- interface.
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:- import_module io.
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:- pred main(io::di, io::uo) is det.
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:- implementation.
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:- import_module int.
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:- import_module list.
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:- import_module solutions.
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:- pragma require_feature_set([memo]).
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main(!IO) :-
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solutions(p, SolnsP),
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io.write_string("P = ", !IO),
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io.write(SolnsP, !IO),
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io.write_string("\n", !IO),
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solutions(q, SolnsQ),
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io.write_string("Q = ", !IO),
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io.write(SolnsQ, !IO),
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io.write_string("\n", !IO),
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solutions(r, SolnsR),
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io.write_string("R = ", !IO),
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io.write(SolnsR, !IO),
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io.write_string("\n", !IO).
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:- pred p(int::out) is nondet.
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:- pragma minimal_model(p/1).
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p(X) :-
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(
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p(Y),
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X = 2 * Y,
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X < 20
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;
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q(X)
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).
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:- pred q(int::out) is nondet.
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:- pragma minimal_model(q/1).
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q(X) :-
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(
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X = 1
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;
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q(Y), % suspend execution -- q is its own leader here
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X = 3 * Y,
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X < 20
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;
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r(X)
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).
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:- pred r(int::out) is nondet.
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:- pragma minimal_model(r/1).
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r(X) :-
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(
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X = 1 % r is its own leader at this point
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;
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q(Y), % here a coup takes place -- leader becomes q
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X = 4 * Y,
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X < 20
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;
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p(Y), % another coup takes place -- leader becomes p
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X = 5 * Y,
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X < 20
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).
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