Outside Passed Pawn

Lessons and training positions emerged from another game with Ryan Ackerman. I traded our last bishops off the board to create a king and pawn endgame. I had a four to three majority on the kingside, but he had a passed a-pawn.

An outside passed pawn usually means a positional advantage sufficient to win. This pawn will draw off the enemy king, allowing our own king to be the first to attack the enemy pawns.
Mark Dvoretsky, Dvoretsky's Endgame Manual, 44.

From this assertion, Dvoretsky goes on to mention several exceptions, including Hansen-Nimzovitch:

Black to move


White threatens to play c2-c3, creating a passed a-pawn. Yet, Black won this game by activating his king.

In the game against Ryan, he pushed his a-pawn at the right moment, his king took care of my majority, and my king was too far away to do anything about his last pawn.

After the game, he created a position for us to explore further.

White to move


Playing around with an old version of Fritz on a slow computer, Black managed to draw this game once. But, most of our efforts resulted in White wins. Can Black draw with best play?


Explorations in History

Looking through my database for similar problems, I found these positions from the nineteenth century.

From Kolisch-Shumov, St. Petersburg 1862

Black to move


White has just played 45.Rxa2, to which Black replied 45...Rxa2. Does the resulting king and pawn endgame give White a decisive advantage?


From Tarrasch-Berger, Breslau 1889

White to move


Tarrasch played 36.Qxf8+!? Does this queen exchange maintain a decisive advantage?


From Weiss-Mason, Breslau 1889

Black to move


Mason played 27...Rxe6. Does this exchange of rooks give White a winning king and pawn endgame?