Re: is there a better way to do constraint logic programming in Mathematica?

*To*: mathgroup at smc.vnet.net*Subject*: [mg80834] Re: is there a better way to do constraint logic programming in Mathematica?*From*: "Dana DeLouis" <dana.del at gmail.com>*Date*: Tue, 4 Sep 2007 03:36:05 -0400 (EDT)

Would this brute-force method be of interest? The logic might not be totally correct, but should be easy to adjust. fx[num_] := Module[ {tot = Round[9*num/2], ip}, Print["Total: " <> ToString[tot]]; ip = IntegerPartitions[tot, {num}]; Select[ip, Length[#] == Length[Union[#]] &]] fx[5] Total: 22 {12,4,3,2,1}, {11,5,3,2,1}, {10,6,3,2,1}, {10,5,4,2,1}, {9,7,3,2,1}, {9,6,4,2,1}, {9,5,4,3,1}, {8,7,4,2,1}, {8,6,5,2,1}, {8,6,4,3,1}, {8,5,4,3,2}, {7,6,5,3,1}, {7,6,4,3,2} Timing[fx[7]] Total: 32 {0.015, {11,6,5,4,3,2,1}, {10,7,5,4,3,2,1}, {9,8,5,4,3,2,1}, {9,7,6,4,3,2,1}, {8,7,6,5,3,2,1} -- HTH :>) Dana DeLouis "sdw" <warwick at jps.net> wrote in message news:fbar15$qft$1 at smc.twtelecom.net... > > simplified constraint programming example in Mathematica: > > find a set of numbers that add to a particular value - numbers cannot be > the same > > note huge timing problem as we go up in variables > > Above 5, it hung... > > > I was really hoping Mathematica had a decent constraint solver, but not sure > now!! > > ---- > > > sumgroup[num_] := (vars = > Flatten @ Table[ ToExpression["x" <> ToString[i]], {i, 1, num}] ; > r1 = And @@ Map[( 0 < # < 10) & , vars]; Print [r1]; > r2 = ( Plus @@ vars) == Round[ 9 num /2]; Print [r2]; > r3 = And @@ Rest @Union @ > Flatten @ Table[vars[[i]] != vars[[j]], {i, 1, num}, {j, i, num}] ; > Print[r3]; > tim = Timing[FindInstance[r1 && r2 && r3, vars, Integers]]; > Print[tim] ; Print[]); > > > > For[ nn = 2, nn < 6, nn++, sumgroup[nn]] > <snip>