[Choco-users] RealVar & implies()

[Michael P. <mpr...@ex...>]

I'm having a problem with RealVar and the Problem.implies() - it doesn't
seem to get applied.  Here's a test with integer bound variables:
 
 public static void main(String[] args) {
  Problem p = new Problem();
 
  p.setPrecision(0.01);
  IntDomainVar height = p.makeBoundIntVar("Height", 1, 100);
  IntDomainVar weight = p.makeBoundIntVar("Weight", 1, 100);
 
  Constraint weightIsDoubleHeight = p.geq(weight, p.mult(2, height));
  
  Constraint tall = p.geq(height,44);
  Constraint weightIsTripleHeight = p.geq(weight, p.mult(3, height));
 
  Constraint tallImpliesHeavy = p.implies(tall,weightIsTripleHeight);
  
  p.post(weightIsDoubleHeight);
  p.post(tallImpliesHeavy);
  
  System.out.println(p.pretty());
 
  if (p.maximize(height, false)) {
   System.out.println(height.pretty());
   System.out.println(weight.pretty());
  } else {
   System.out.println("No solution.");
  }
 }

This works correctly, producing a solution of height=43 and weight=86.
 
When I switch over to RealVar, the implies constraint,
'tallImpliesHeavy', no longer works.
 
 public static void main(String[] args) {
  Problem p = new Problem();
 
  p.setPrecision(0.01);
  RealVar height = p.makeRealVar("Height", 1, 100);
  RealVar weight = p.makeRealVar("Weight", 1, 100);
 
  Constraint weightIsDoubleHeight = p.geq(weight, p.mult(p.cst(2),
height));
 
  Constraint tall = p.geq(height,44);
  Constraint weightIsTripleHeight = p.geq(weight, p.mult(p.cst(3),
height));
 
  Constraint tallImpliesHeavy = p.implies(tall,weightIsTripleHeight);
  
  p.post(weightIsDoubleHeight);
  p.post(tallImpliesHeavy);
  
  System.out.println(p.pretty());
 
  if (p.maximize(height, false)) {
   System.out.println(height.pretty());
   System.out.println(weight.pretty());
  } else {
   System.out.println("No solution.");
  }
 }

This produces an answer of height= approx. 50, and weight=approx. 100.
 
Any insight would be helpful.
 
Michael
 

Michael Prescott
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