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Added some comments for the symmetry breaking #16

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24 changes: 19 additions & 5 deletions symmetry/wind/wind.mzn
Original file line number Diff line number Diff line change
Expand Up @@ -37,13 +37,27 @@ output [ "tributes: \n"] ++ [( if j > n then "\n" else show(tribute[i, j]) ++ "
] ++
["matching: (m = ", show(m), ", n = ", show(n), ", tcoins = ", show(tcoins), ")\n"];

% variable symmetry breaking
%constraint forall(j in 1..n-1)(
% variable symmetry breaking;

% Variable symmetry breaking 1: Impose arbitrary order on outgoing branches,
% with the lex-min outgoing branch the one numbered 1:

% constraint forall(j in 1..n-1)(
% lex_lesseq([tribute[i,j] | i in POLYGON],
% [tribute[i,j+1] | i in POLYGON])
% );

%constraint lex_lesseq([tribute[i,j] | i in 1..round(m div 2), j in VERTEX], [tribute[m+1-i,j] | i in 1..round(m div 2), j in VERTEX]);
% Simpler:

constraint forall(j in 1..n-1)
(tribute[1,j] < tribute[1,j+1]);
constraint tribute[1,1] < tribute[m,1];
(tribute[1,j] < tribute[1,j+1]);

% Variable symmetry breaking 2: Impose arbitrary order between innermost and outermost
% polygon tribute sequence, with the innermost sequence the lex-lesser of the two:

% constraint lex_lesseq([tribute[i,j] | i in 1..round(m div 2), j in VERTEX],
% [tribute[m+1-i,j] | i in 1..round(m div 2), j in VERTEX]);

% Simpler:

constraint tribute[1,1] < tribute[m,1];