Debby (Mona + YL)  vs  Kerry Handscomb   March 23 - April 5, 2000

   1. b1-b3 a2-c2   2. g1-e3 h5-f7   3. c1-f4 h6:f8   4. b8-e5 h7-e7
   5. e1-e6 c2-c4   6. f1:c4 a6:c4   7. c8-f5 a7-d7   8. d1:a4 d7-g7
   9. e8-c6 g7:e5  10. g8-g7 e5:g7  11. d8-d7 Resigns 1-0

  Move by Move:

 Note that Kerry's comments are taken from the e-mail messages
 during the game, without the benefit of hindsight.  This allows
 some insight into how a top level Lines of Action player thinks.

      +-----------------+
    8 | . B B B B B B . |
    7 | W . . . . . . W |
    6 | W . . . . . . W |
    5 | W . . . . . . W |
    4 | W . . . . . . W |
    3 | W . . . . . . W |
    2 | W . . . . . . W |
    1 | . B B B B B B . |
      +-----------------+
        a b c d e f g h	 

    1. b1-b3 a2-c2
 
 Kerry:  1. b1b3 is my least favourite opening move to play against as
 it holds back my preferred opening strategy.  I'm tempted to ignore
 d1:a4 and play a5c7 anyway, but I had better be prudent as I don't know
 how strong Debby is yet.

 Darse:  When this game began, both YL and Mona played 1. b1-b3 at all
 search depths.  Later, after the introduction of blocking moves to the
 evaluation function, YL began playing 1. d1-b3, and the play took on a
 more "human" look.  This move is preferred by Kerry and several other
 strong players.  After the addition of blockading knowledge, Mona also
 plays 1. d1-b3 at certain depths, and follows up with full blockades.

      +-----------------+
    8 | . B B B B B B . |
    7 | W . . . . . . W |
    6 | W . . . . . . W |
    5 | W . . . . . . W |
    4 | W . . . . . . W |
    3 | W B . . . . . W |
    2 | . . W . . . . W |
    1 | . . B B B B B . |
      +-----------------+
        a b c d e f g h  

    2. g1-e3 h5-f7

    depth value best  principle variation (last 4-ply deleted)

 YL:    9       g1e3 h6f6 b8b6 h7f7 f8d6
 Mona: 10   40  g1-e3 h6-f6 f1-f4 a3-c5 b8-e5 a5:e5

 alternate choice:
 YL:    9  +82  e8g6 h3e3 g1g4 a7c5 f8c5
 Mona: 10  -26  e8-g6 a7-c7 b8-b6 h2-f4 g8-e6 h3-e3

 Darse:  YL prefers the blockading move e8-g6, but Mona did not yet have
 the type of knowledge that would lead to such a move, and therefore did
 not give it much credit.  For that reason, the computer "plan" for this
 game will be to control the center and play for tactics.

 A note about the minimax scores:

 The two programs use different scales, so their scores should not be
 compared directly.  A score of about +300 by Mona or +100 by YL usually
 indicates a clear advantage.  There is a significant odd-even effect, so
 these odd-ply values are likely to be optimistic (for Mona, too high by
 at least 50 points).

 Mona indicates a mate threat with a +1000 bonus, so a score of 3150
 indicates a small positional advantage and a triple threat to connect.
 Only certain types of mate threats are detected statically, so there
 could be more in a given position.  Mona reserves 0 (zero) for a draw
 and 32000 for a win.  YL uses 30000 for a win, minus the number of moves
 to mate, so a score of -29988 means a loss in 12-ply.

      +-----------------+
    8 | . B B B B B B . |
    7 | W . . . . W . W |
    6 | W . . . . . . W |
    5 | W . . . . . . . |
    4 | W . . . . . . W |
    3 | W B . . B . . W |
    2 | . . W . . . . W |
    1 | . . B B B B . . |
      +-----------------+
        a b c d e f g h  

    3. c1-f4 h6:f8

 YL:   13  +27  c1f4 h7e7 g8g7 a3d6 b8b6 h3e3 d1d4 h4f2 f1d3
 Mona: 11  100  c1-f4 h7-e7 d1-d3 a3-d6 b8-b6 a7-d7 f1-c4

 Kerry:  I like material gains and I don't like to take the centre early
 on as you can be attacked too easily, but I haven't done any analysis of
 this position.

      +-----------------+
    8 | . B B B B W B . |
    7 | W . . . . W . W |
    6 | W . . . . . . . |
    5 | W . . . . . . . |
    4 | W . . . . B . W |
    3 | W B . . B . . W |
    2 | . . W . . . . W |
    1 | . . . B B B . . |
      +-----------------+
        a b c d e f g h	 

    4. b8-e5 h7-e7

 YL:   13 +110  b8e5 a7d7 g8g7 a6c4 d8f6 a4e4 c8c5 f8c5 g7d4
 Mona: 11  168  b8-e5 h3:f1 d8-f6 h4:f6 e8-c6 a4:c6 c8:f8

 other moves:
 Mona: 11  175  g8-g7 f8-d6 g7-f6 c2-e2 f1:h3 h7-e7 h3-f5
 Mona: 11  176  e8-e5 h3:f1 g8-g7 f8:f4 b3-d5 h2-f2 d1-d4

 Kerry:  I think the build-up in the centre is interesting.  Debby
 obviously likes to move toward the centre from the corner squares.
 I have the option to continue building my position or start attacking.

      +-----------------+
    8 | . . B B B W B . |
    7 | W . . . W W . . |
    6 | W . . . . . . . |
    5 | W . . . B . . . |
    4 | W . . . . B . W |
    3 | W B . . B . . W |
    2 | . . W . . . . W |
    1 | . . . B B B . . |
      +-----------------+
        a b c d e f g h  

    5. e1-e6 c2-c4

 YL:   14  +71  e1e6 f8f4 f1f4 a4c6 e8c6 h4f4 g8g7 a3c5 d8d6 c2c6
 Mona: 11  230  e1-e6 a6-c4 g8-h7 h3:e6 c8:e6 h2-h5 d1-d3

 Kerry:  I saw e1e6, but not the threat b3:f7.  No choice here.

 Darse:  If 5... a7-d7?? then mate follows in 8-ply:
 eg. b3:f7 h3:e3 d1-d4 d7:d4 g8-d5 a5:d5 f1-f5 a6-c4

 Black is threatening mate in 11-ply, so White must not allow b3:f7.

      +-----------------+
    8 | . . B B B W B . |
    7 | W . . . W W . . |
    6 | W . . . B . . . |
    5 | W . . . B . . . |
    4 | W . W . . B . W |
    3 | W B . . B . . W |
    2 | . . . . . . . W |
    1 | . . . B . B . . |
      +-----------------+
        a b c d e f g h  

    6. f1:c4 a6:c4

 YL:   13  +91  f1c4 h3e6 c8e6 a7d7 g8g7 a6c4 e6f6 a4e4 g7d4
 Mona: 11  209  f1:c4 f7:f4 d8-d6 a6:d6 d1-d3 h4-d4 d3-e4

 alternate choice:
 YL:   13  +78  f1f5 a7d7 c8c6 h4h7 c6d5 h7f5 g8h7 f8f4 d8b8
 Mona: 11  247  f1-f5 a6-c6 d8-d6 h4-f6 c8-g4 a3-b2 g8-g6

 Darse:  After accounting for the inflation of Mona's ratings relative
 to YL's, the averages for the two moves are very close.  Playing down
 the PVs two or three moves and doing another search suggested that the
 values for f1-f5 might be dropping, while f1:c4 held steady.

 I was surprised that such sharp lines (eg. possible mates) would even
 exist this early in the game, so I asked Kerry if this was normal.

 Kerry:  Yes, it's quite common to have sharp lines quite early.  But this
 whole combination took me by surprise.  I have a fight to survive now.

      +-----------------+
    8 | . . B B B W B . |
    7 | W . . . W W . . |
    6 | . . . . B . . . |
    5 | W . . . B . . . |
    4 | W . W . . B . W |
    3 | W B . . B . . W |
    2 | . . . . . . . W |
    1 | . . . B . . . . |
      +-----------------+
        a b c d e f g h	 

    7. c8-f5 a7-d7

 YL's search (unavailable) gave a strong preference for c8-f5.
 Mona: 12  139  c8-f5 a3-d6 g8-g7 h3:e3 d1-e2 a5-d5 g7-g6 a4-c6

 Mona: 13  155  d1-d3 a7-d7 f4:f7 a3-d6 e3-f4 h3-h6 b3-d1 h6:f4 f7:f4

 Kerry:  I was expecting 7. f4:f7 after which there would have been a
 fierce tactical battle.  Because of Debby's number-crunching abilities
 I could have lost this battle.  Unless I am surprised again, Debby has
 left me the chance to fight the game on a strategic basis.

 Darse: Several other moves were considered, but the simple f4:f7 was
 not among them.  Although later analysis suggests that f4:f7 was not
 overwhelming against best play, this nevertheless revealed a serious
 weakness in both programs.  This game, more than any other factor,
 prompted the addition of blockading knowledge to both programs.

 Like most game programs based on minimax (alpha-beta) search, they
 implicitly assume that the opponent sees everything they see.  So if
 the tactics eventually settle within the depth of analysis, it might
 prefer a quiet move that does not test the opponent. Naturally, this
 is not always desirable against a human, since they are fallible.

      +-----------------+
    8 | . . . B B W B . |
    7 | . . . W W W . . |
    6 | . . . . B . . . |
    5 | W . . . B B . . |
    4 | W . W . . B . W |
    3 | W B . . B . . W |
    2 | . . . . . . . W |
    1 | . . . B . . . . |
      +-----------------+
        a b c d e f g h  

    8. d1:a4 d7-g7

 YL:   15  +77  d1a4 d7d5 b3f3 h4h7 f3d5 h7f5 e8c6 h2g2 e3d4 a3d6
 Mona:  9  218  d1:a4 h4-h7 g8-g7 h7:f5 a4:d7

 alternate choice:
 Mona: 13  203  g8-g7 a4-e4 g7-g6 h2-g1 d1-d4 a5-d5 d8-a8 h3-g2 a8-d8

 Kerry:  I'm having to spend too much time defending.

 Darse:  YL looked at 1.7 billion positions to complete our first 15-ply
 search.  This later became fairly routine for YL in the middle game.

 The very close alternative move was the simple g8-g7, but playing
 down the PVs and repeating the search made the capture preferable.
 In hindsight, the capture is much stronger, as it puts pressure on
 the White blockade.  Neither program understood this at the time,
 but now they handle this strategic aspect of the game much better.
 For example, the strong reply d7-g7 (shifting the blockade to the
 g8 piece) did not appear in any of the PVs of either program; but
 the subsequent versions of Mona expect this reply, even at 7-ply.

      +-----------------+
    8 | . . . B B W B . |
    7 | . . . . W W W . |
    6 | . . . . B . . . |
    5 | W . . . B B . . |
    4 | B . W . . B . W |
    3 | W B . . B . . W |
    2 | . . . . . . . W |
    1 | . . . . . . . . |
      +-----------------+
        a b c d e f g h  

    9. e8-c6 g7:e5

 YL:   14  +59  e8c6 a5d5 e3e7 a3d6 e7e4 g7e5 g8g7 h4f6 d8f6 h2h4
 Mona: 13  226  e8-c6 a5-d5 d8-d6 f8-h6 b3-f3 a3:d6 f3:f7 h6-f8 c6:c4

 Kerry:  Complicated position.  I looked at h4-h7, but I couldn't see
 through all the possibilities.  Intuitively, the grab for the piece on
 e5 makes Debby's position look quite strung out.

 Darse:  The programs often get positions that look strung out, since they
 strive for piece activity more than the formation of groups (which is
 accomplished pretty much indirectly).  However, bringing those scattered
 pieces together efficiently is a computational task, and they seem to be
 quite good at that aspect of the game.

      +-----------------+
    8 | . . . B . W B . |
    7 | . . . . W W . . |
    6 | . . B . B . . . |
    5 | W . . . W B . . |
    4 | B . W . . B . W |
    3 | W B . . B . . W |
    2 | . . . . . . . W |
    1 | . . . . . . . . |
      +-----------------+
        a b c d e f g h	 

   10. g8-g7 e5:g7

 YL:   15 +122  g8g7 a5d5 d8d6 a3a1 c6c4 a1d4 c4d3 f7g6 b3f3 e7g5 a4b3
 Mona: 13  401  g8-g7 a3-b2 c6:c4 f7-g6 d8:f8 a5-d5 e6:g6 h2-f2 f5-d3

 alternate choice:
 Mona: 13  445  c6:c4 e7-g7 a4-e4 a5-d5 e3-d4 f7-d7 e6-f6 h2-h5 d8-g5

 Darse:  A +300 evaluation by Mona usually indicates a clear advantage.
 A +100 rating by YL also indicates an advantage, but not as convincing.

 Kerry:  I think Debby has the advantage.  I have to rely on a mistake now. 

      +-----------------+
    8 | . . . B . W . . |
    7 | . . . . W W W . |
    6 | . . B . B . . . |
    5 | W . . . . B . . |
    4 | B . W . . B . W |
    3 | W B . . B . . W |
    2 | . . . . . . . W |
    1 | . . . . . . . . |
      +-----------------+
        a b c d e f g h  

   11. d8-d7 Resigns

 YL announces mate in 13-ply, (see continuation shown below) PV:
 d8-d7 f7-e8 f5-d5 e8-c8 f4-d6 h3-g2 d5-b5 c8-a8 e3-d4 a8:a4 c6:c4 a3-a6 d4-c5

 Mona finds an alternate mate in 13-ply, PV:
 c6:c4 f7-c7 f5-d5 h3-f5 a4-b5 a3-d6 d8:f8 g7-f6 f8-e8 c7-c5 e8-c6 c5:e3 b5:f5

 Mona verifies the mate after 11. d8-d7, PV:
 d8-d7 f7-e8 f4-d6 c4:c6 a4-c4 h3-h6 c4-e4 g7-g8 f5-d5 a5-a7 b3-c2 a7:d7 c2-c4

 Some of the other lines reported by Mona include:
 d8-d7 h2:f4 c6:c4 h4-d4 f5-d5 a3-d6 d7-b5 g7-e5 b5-d3
 d8-d7 a3-d6 c6:c4 f7-e8 f5-d5 a5-b4 a4-c2 h3:e6 d7-b5 e7:e3 f4:b4
 d8-d7 f7-e8 c6:c4 f8:f5 a4-e4 e8-f7 b3-f3 h4-h1 d7-d6 a3:d6 c4-d3 h1-h4 f3-d5

 c6:c4 h2:f4 d8-d7 h4-d4 f5-d5 a3-d6 d7-b5 g7-e5 b5-d3
 c6:c4 g7-d7 d8-b6 f8-c5 b6-d6 c5:f5 d6-d4 f7:f4 e6-d6 h2-e5 d6-d3
 c6:c4 f7-c7 f5-d5 h3-f5 a4-b5 a3-d6 d8:f8 g7-f6 f8-e8 c7-c5 e8-c6 c5:e3 b5:f5

 Darse:  I don't think the move 10... e5:g7 is technically a mistake.
 I played out many games with different defenses, including that one,
 and they all resulted in a win for Black.  That isn't a proof, but
 it looks like the position may be untenable after 9... g7:e5.

 Prior to that, there were several test games that ended in a win for
 White, and this is how we determined some of the limitations of the
 evaluation functions.  I have since made changes that should help
 Mona avoid dangerous blockades, or at least attack them if they are
 formed.  We're both very thankful for this instructive game!

 Kerry:  OK, I concede defeat.  Now I know what I'm up against.  I didn't
 play carefully enough in the first game and made a couple of errors.  I
 would like the opportunity for a rematch.  My turn to move first: 1. d1b3.

      +-----------------+       +-----------------+       +-----------------+
    8 | . . . . . W . . |     8 | . . W . . W . . |     8 | . . W . . W . . |
    7 | . . . B W W W . |     7 | . . . B W . W . |     7 | . . . B W . W . |
    6 | . . B . B . . . |     6 | . . B . B . . . |     6 | . . B B B . . . |
    5 | W . . . . B . . |     5 | W . . B . . . . |     5 | W . . B . . . . |
    4 | B . W . . B . W |     4 | B . W . . B . W |     4 | B . W . . . . W |
    3 | W B . . B . . W |     3 | W B . . B . . W |     3 | W B . . B . . . |
    2 | . . . . . . . W |     2 | . . . . . . . W |     2 | . . . . . . W W |
    1 | . . . . . . . . |     1 | . . . . . . . . |     1 | . . . . . . . . |
      +-----------------+       +-----------------+       +-----------------+
        a b c d e f g h           a b c d e f g h           a b c d e f g h  

  YL PV:       
    f7-e8 f5-d5 e8-c8
          f4-d6 h3-g2
          d5-b5 c8-a8

      +-----------------+       +-----------------+       +-----------------+
    8 | W . . . . W . . |     8 | . . . . . W . . |     8 | . . . . . W . . |
    7 | . . . B W . W . |     7 | . . . B W . W . |     7 | . . . B W . W . |
    6 | . . B B B . . . |     6 | . . B B B . . . |     6 | W . . B B . . . |
    5 | W B . . . . . . |     5 | W B . . . . . . |     5 | W B . . . . . . |
    4 | B . W . . . . W |     4 | W . W B . . . W |     4 | W . B B . . . W |
    3 | W B . . B . . . |     3 | W B . . . . . . |     3 | . B . . . . . . |
    2 | . . . . . . W W |     2 | . . . . . . W W |     2 | . . . . . . W W |
    1 | . . . . . . . . |     1 | . . . . . . . . |     1 | . . . . . . . . |
      +-----------------+       +-----------------+       +-----------------+
        a b c d e f g h           a b c d e f g h           a b c d e f g h  

  YL PV:  e3-d4 a8:a4
          c6:c4 a3-a6
          d4-c5++