RE: [Help-glpk] information on presolve results

[iimk]

Was solving a puzzle using glpk and wanted to model logical constraints.

Glpsol says : "Operand preceding = has invalid type"

Context: s.t. third : if truth[3]=1.......

Can't the if operator be used this way?

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set N ;

var own {n in N}, binary;

var mentions{n in N},binary;

var truth{n in N}, binary;

maximize obj: mentions[1];

subject to first:  truth[1]=own[3];

s.t. second: truth[2]=1-own[2];

s.t. third : if truth[3]=1 then sum{n in N}truth[n]=1;

s.t. CA:( if truth[3]=1 and mentions[1] then own[1] else(1- own[1]))=1;

s.t. CB:if (truth[3]=1 and mentions[2]) then own[2]=1 else(1- own[2])=1;

s.t. CC:if (truth[3]=1 and mentions[3]) then own[3]=1 else(1- own[3])=1;

s.t. owner:sum{n in N}own[n]=1;

s.t. cmentions: sum{n in N}mentions[n]=1;

data;

set N :=1 2 3;

end;

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