Triangulation

   White wants to get his King to b6, to do this he must bring about the same position in the diagram, but with Black to move.  He does this by "Triangulation".

 

 

 

 

After 1.Kd5  Kc8,  2.Kd4! White is now ready to meet 2...Kc7 with 3.Kc5 and follow it up with 4.Kb6 winning Black's a6-pawn.

 

 

 

 

 

 

2...Kd8, 3.Kc4 (still waiting for 3...Kc7).  3... Kc8,  4.Kd5 Kc7 and now we have the the position in the diagram--but with Black to move.