In the august update of the 1.e4,e5 section IM Wallace has added an interesting analysis of the game Adams-Smeets. One analysis position attracted my attention

diagram I
http://www.france-echecs.com/diagramme/imgboard.phpfen=8/2p4p/7P/1k2K3/8/5P2/8/8...
8/2p4p/7P/1k2K3/8/5P2/8/8 w - - 

This is the final position of an analysis line. IM Wallace comments:
"and White wil l emerge with an extra h-pawn in a queen endgame. although I am not enough of an expert to say with any certainty whether it is a win or a draw!"

This is a bit of a superficial judgement as no further analysis is added, and it is not clear how white will reach the indicated endgame. So let's see if we can find out something more about this position.

First of all: when looking at the pawn structure, we should remember two basic pawn endgames. These endgames may easily occur after exchanging some pawns (or queens for that matter).

support position S1.

http://www.france-echecs.com/diagramme/imgboard.phpfen=8/4k1Kp/7P/8/8/8/8/8w--
8/4k1Kp/7P/8/8/8/8/8 w - -

This position is drawn. The moment white takes the h-pawn, black imprisons the white king.
1.Kxh7, Kf7 draw
In fact with only the h-pawns remaining on the board, black has a draw if his king can play Kc7/Kc8 immediately after white takes on h7.

support postion S2.

http://www.france-echecs.com/diagramme/imgboard.phpfen=8/7p/5k1P/8/4KP2/8/8/8w--
8/7p/5k1P/8/4KP2/8/8/8 w - -

Just think of this position without the h-pawns: it's a book draw.

After this introduction were ready to attack the endgame. It's quite easy to get bogged down with
all kind of long confusing variations. So lets first look at the plans white has at his disposal:

Plan A.  First ensure that the white king can hold up black's passed pawn.
Plan B.  Immediately start a pawn race. White plans to promote the f-pawn.
Plan C.  White goes after the h-pawn first, and plans to promote his own h-pawn.


Plan A. First ensure that the white king can hold up black's passed pawn.

This plan in fact puts white at risk. Starting of with Kd4 or Ke4 gives black time to bring his King into the square of the f-pawn. In fact it gives black a position where he has an outside passed pawn, and thus has the advantage in the pawn endgame.

Plan B.  Immediately start a pawn race. White plans to promote the f-pawn.

1.f4,....
1...., c5      The only move. Black has no time for 1....Kc6 as 2.Ke6! wins easily for white.
                Black has obstructed his on free c-pawn, without any chance of holding up white's f-pawn
                In fact he has lost a very valueble tempo and is now lost.
2.f5!          
2.... ,c4      2....Kc6 is a bad idea.  White again continues with 3.Ke6,c4
                Then the pawn-race starts After three more moves white has a queen on f8,black on c1.
                But it is white to move and due to the unfortunate position of the black king
                7.Qc8+ picks up the black queen allong the c-line.
3.f6,           White may think that it's now time to force blacks king to b4, so he may queen with check.
                 (3.Kd4,Kb4 4.f6,c3 5.f7,c2 6.f8Q+) but black need not comply:
                 3.Kd4,Kc6! 4.Kxc4, Kd6 5.Kd4,Ke7 6.Ke5,Kf7 and we have reached support position S2
                 drawn.
3....,c3
4.f7,c2
5.f8Q,c1Q   


diagram II
http://www.france-echecs.com/diagramme/imgboard.phpfen=5Q2/7p/7P/1k2K3/8/8/8/2q5...
5Q2/7p/7P/1k2K3/8/8/8/2q5 w - -

The pawn race has ended with two queens. However I dont see any way for white to reach an 
advantage. 
The following variations are important, illustrating that black can afford to exchange queens.
6.Qe8+,Qc6 7.Qxc6,Kxc6 drawn as black easily reaches support postion S1 drawn.
6.Qb8+,Ka6! 7.Qa8+,Kb8 8.Qd8+,Qc7+ 9.Qx7,Kx7 again reaching support postion S1 drawn

Plan C.  White goes after the h-pawn first, and plans to promote his own h-pawn.

1.Kf6!, c5
2.Kg7, c4
3.Kxh7,c3
4.K??,c2
5.h7,c1Q
6.c8Q



There is a reason why I have not filled in white's king position. White has two basic choices:
C1. Kg8/g7 This allows black to exchange queens at once
C2. Kg6  This is the toughest nut to crack.

diagram III
http://www.france-echecs.com/diagramme/imgboard.phpfen=6KQ/8/8/1k6/8/5P2/8/2q5b-...
6KQ/8/8/1k6/8/5P2/8/2q5 b - -

White's plan C1

6....., Qc8+
6.Kg7,Qxh8+
7.Kxh8.Kc5

diagram IV
http://www.france-echecs.com/diagramme/imgboard.phpfen=7K/8/8/2k5/8/5P2/8/8w--
7K/8/8/2k5/8/5P2/8/8 w - -

This postion is drawn. Black requiers only three moves to take the f-pawn.
The white king needs four moves to protect the f-pawn.

Whites plan C2.

diagram V
http://www.france-echecs.com/diagramme/imgboard.phpfen=7Q/8/6K1/1k6/8/5P2/8/2q5b...
7Q/8/6K1/1k6/8/5P2/8/2q5 b - -

White has a plus pawn, and a direct simplification into a drawn pawn endgame is not available.
Black now must choose how he aims to hold the draw.
One characteristic of this position stands out: White's queen has an inactive position.
For black it's a bad policy to allow the queen back into the game
So black should steer clear of 6....Qc6+? 7.Qf6, Qe8+ 8.Kh6 when he has allready run out of usefull
checks.

Much more sensible is to check allong diagonals if possible because it prevents white to interpose with his own queen.

6........  Qc2+!
7.Kg5.                  White plans to hide his king in the neighbourhood of the f-pawn.
                          His other plan of action is to try to hide his king on the queenside.
                          But this is not feasable: 7.Kf7,Qb3+ allready drops the f-pawn 
                          7.Kf6,Qb2 drops the queen and 7.Kg7,Qg7+ tranposes back to C1 
                          black exchanging queens.
7......,  Qg2+        Forcing white to protect the f-pawn
7.Kf4,  Qd2+         
8.Kg3,                  Other king-moves dont bring anything: 7.Ke4,Qe2+ 8.Kf4,Qd2+ repeating
                          7.Kf5,Qc2+ 8.Ke6,Qb3 (see note to white's 7th move)
8......,  Qg5+        And it is not feasible for white to excape out of the e1-e4-h4-h8 quadrant.

Conclusions:
1. The initial position is drawn.
2. It can save a lot of calculation to take a sensible look at the possible (plausible) basic pawn endgames.