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I have a set of constraints to which I require integer solutions. However, instead of needing all possible integer solutions (as obtained by using Solve[constraints,Variables,Integers]), I need any one solution only.

Here is a specific example:

variables = {
  Subscript[x, 11], Subscript[x, 12], Subscript[x, 13],
  Subscript[x, 14], Subscript[x, 15], Subscript[x, 16]
};

constraints = 
  273 + 4 Subscript[x, 11] + Subscript[x, 12] >= 0 &&
  -693 - 8 Subscript[x, 11] - 3 Subscript[x, 12] + Subscript[x, 13] >= 0 && 
  483 + 4 Subscript[x, 11] + 3 Subscript[x, 12] - 3 Subscript[x, 13] +
    Subscript[x, 14] >= 0 &&
  -Subscript[x, 12] + 3 Subscript[x, 13] - 3 Subscript[x, 14] + Subscript[x, 15] >= 0 &&
  -Subscript[x, 13] + 3 Subscript[x, 14] - 3 Subscript[x, 15] + 24 Subscript[x, 16] >= 0 &&
  -Subscript[x, 14] + 3 Subscript[x, 15] - 32 Subscript[x, 16] >= 0 &&
  -Subscript[x, 15] + 8 Subscript[x, 16] >= 0 &&
  Subscript[x, 16] >= 0 &&
  Subscript[x, 11] >= 0 &&
  462 + 11 Subscript[x, 11] + Subscript[x, 12] + Subscript[x, 13] + Subscript[x, 14] + 
    Subscript[x, 15] - 15 Subscript[x, 16] >= 0 &&
  2709 + 42 Subscript[x, 11] + 8 Subscript[x, 12] + 4 Subscript[x, 13] -
    4 Subscript[x, 15] + 40 Subscript[x, 16] >= 0 &&
  4536 + 54 Subscript[x, 11] + 18 Subscript[x, 12] - 2 Subscript[x, 13] - 
    6 Subscript[x, 14] + 6 Subscript[x, 15] - 45 Subscript[x, 16] >= 0 &&
  -1134 - 27 Subscript[x, 11] - 12 Subscript[x, 13] + 8 Subscript[x, 14] -
    4 Subscript[x, 15] + 24 Subscript[x, 16] >= 0 &&
  -6318 - 81 Subscript[x, 11] - 27 Subscript[x, 12] + 9 Subscript[x, 13] - 
    3 Subscript[x, 14] + Subscript[x, 15] - 5 Subscript[x, 16] >= 0 &&
  273 + 4 Subscript[x, 11] + Subscript[x, 12] == Subscript[x, 16] &&
  -693 - 8 Subscript[x, 11] - 3 Subscript[x, 12] + Subscript[x, 13] == Subscript[x, 11];

solutions = Solve[constraints, variables, Integers]

I get an output, but it is very long as there are many solutions. Consequently, the runtime is significant. Hence, I want to modify Solve[] as to stop evaluating after one solution has been found. I believe that would not run for as long as the general case.

Could anyone please help me?

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1 Answer 1

up vote 6 down vote accepted

This can be done using FindInstance:

solutions = FindInstance[constraints, variables, Integers]

(*
==> {{Subscript[x, 11] -> 5, Subscript[x, 12] -> -293, 
  Subscript[x, 13] -> -141, Subscript[x, 14] -> -47, 
  Subscript[x, 15] -> -6, Subscript[x, 16] -> 0}}
*)
share|improve this answer
    
Great !! Thanks a lot. –  Pavithran Iyer Mar 4 '13 at 0:51

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