bernasconi
minco
scip
ZIMPL
,<2,4>,<3,5>,<4,6>,<5,7>,<6,8>,<7,9>,<8,10>,<9,11>,<10,12>,<11,13>,
<12,14>,<13,15>,<14,16>,<15,17>,<16,18>,<17,19>,<18,20> };
set S4 := { 1 .. 20 };
# define weights
param C[S3] := <1,3> 8,<2,4> 8,<3,5> 8,<4,6> 8,<5,7> 8,<6,8> 8,<7,9> 8,<8,10> 8,<9,11> 8,
<10,12> 8,<11,13> 8,<12,14> 8,<13,15> 8,<14,16> 8,<15,17> 8,<16,18> 8,<17,19> 8,<18,20> 8;
param D[S4] := <1> -4,<2> -4,<3> -8,<4> -8,<5> -8,<6> -8,<7> -8,<8> -8,<9> -8,
<10> -8,<11> -8,<12> -8,<13> -8,<14> -8,<15> -8,<16> -8,<17> -8,<18> -8,
<19> -4,<20> -4;
# number of nodes
param nodes := 20;
# nodes
set N := { 1 to nodes };
# variables
var x[N] binary;
var z implicit integer >= -infinity;
# Objective
minimize obj: z;
# interacting constraint
subto interacting_spins:
-z + sum in S3 do C[i,j] * x[i] * x[j]
+ sum in S4 do D[i] * x[i] <= 0;
]]>
This is the example BERNASCONI.20.3 in ZIMPL format from POLIP http://polip.zib.de