PROBLEM Rastrigin

/* Optimize the Rastrigin function. Solutions are full binary trees so the vector x can only have 2^n elements  */  

NONTERMINALS
   F<<out IEnumerable<double> x>>.
  F1<<out IEnumerable<double> x>>.
  F2<<out IEnumerable<double> x>>.
  F3<<out IEnumerable<double> x>>.
  F4<<out IEnumerable<double> x>>.

TERMINALS
  X<<out double val>>
    CONSTRAINTS
      val IN RANGE <<-5.12>> .. <<5.12>>
  .

RULES
  F<<out IEnumerable<double> x>> = LOCAL<< IEnumerable<double> x1, x2; >>
    F1<<out x1>> F1<<out x2>>      SEM<< x = x1.Concat(x2); >>
  .
  F1<<out IEnumerable<double> x>> = LOCAL<< IEnumerable<double> x1, x2; >>
    F2<<out x1>> F2<<out x2>>      SEM<< x = x1.Concat(x2); >>
  .
  F2<<out IEnumerable<double> x>> = LOCAL<< IEnumerable<double> x1, x2; >>
    F3<<out x1>> F3<<out x2>>      SEM<< x = x1.Concat(x2); >>
  .
  F3<<out IEnumerable<double> x>> = LOCAL<< IEnumerable<double> x1, x2; >>
    F4<<out x1>> F4<<out x2>>      SEM<< x = x1.Concat(x2); >>
  .
  F4<<out IEnumerable<double> x>> = LOCAL<< double v; >>
    X<<out v>>                      SEM<< x = Enumerable.Repeat(v, 1); >>
  .

MINIMIZE
  << 
    IEnumerable<double> x;
    F(out x);
    return 10.0 * x.Count() + x.Sum(xi=>xi*xi - 10 * Math.Cos(2*Math.PI*xi));
  >>
END Rastrigin.