[Retros] Pawn to the 7th

[Richard Stanley]

An improvement on Pa6xb7/Pa3xb2 double check (C+). 

  1.d2-d3 c7-c6    2.Bc1-e3 Qd8-a5+  3.Qd1-d2 Qa5*a2  4.Qd2-a5 Qa2*a5+
  5.Sb1-d2 Qa5-b5  6.0-0-0 a7-a5     7.Kc1-b1 a5-a4   8.Kb1-a1 a4-a3 
  9.Rd1-b1 a3*b2 ##

If the last move must be exactly Pa6xb7, then here is one way to do it
in 9.5 moves (C+)

  1.h2-h4 d7-d6    2.Rh1-h3 Qd8-d7  3.Rh3-a3 Qd7-f5  4.Ra3*a7 Bc8-e6
  5.Ra7-a3 Sb8-d7  6.Ra3-b3 0-0-0   7.a2-a4 Kc8-b8   8.a4-a5 Kb8-a8 
  9.a5-a6 Rd8-b8   10.a6*b7 ##

Richard