Author: Ricardo Gibert
Date: 10:11:23 10/19/00
Go up one level in this thread
On October 19, 2000 at 07:04:14, Uri Blass wrote: >On October 19, 2000 at 05:50:54, Ricardo Gibert wrote: > >>On October 19, 2000 at 01:06:03, Uri Blass wrote: >> >>>On October 19, 2000 at 00:51:19, Christophe Theron wrote: >>> >>>>On October 18, 2000 at 16:31:54, Ricardo Gibert wrote: >>>> >>>>>On October 18, 2000 at 15:57:10, Uri Blass wrote: >>>>> >>>>>>On October 18, 2000 at 15:52:09, Ricardo Gibert wrote: >>>>>> >>>>>>>On October 18, 2000 at 14:14:20, Uri Blass wrote: >>>>>>> >>>>>>>>On October 18, 2000 at 12:34:42, Ricardo Gibert wrote: >>>>>>>> >>>>>>>><snipped> >>>>>>>>>The algorithm to determine whether this type of position is drawn is quite >>>>>>>>>simple. With the h-pawn, Black draws if the K can get into the four corner >>>>>>>>>squares g7,g8,h7,h8. Otherwise, the outcome is not assured. Note, it is not >>>>>>>>>enough for the King to get in front of the pawn as the following position >>>>>>>>>illustrates: >>>>>>>> >>>>>>>>I can give another rule: >>>>>>>>Blacks draw if it is black to move and the distance between the black king and >>>>>>>>the corner in king moves is smaller than the ditance between the corner and the >>>>>>>>white pieces except the bishop(white king in king moves and white pawn in pawn >>>>>>>>moves) >>>>>>>> >>>>>>>>If it is white to move then use distance-1 instead of distance for white. >>>>>>>> >>>>>>>>Uri >>>>>>> >>>>>>>I like your rule. It's interesting, but it needs to be amended somewhat: >>>>>>> >>>>>>>[D]4B3/8/8/8/8/2k5/7P/K7 b - - 0 0 >>>>>> >>>>>>This position is not a draw by my rule. >>>>>>The distance of the white pawn to the corner in pawn moves is equal(and not >>>>>>smaller) to the distance of the black king to the corner in king moves. >>>>> >>>>>Yep, I goofed. >>>>> >>>>>> >>>>>>> >>>>>>>as you can see, your rule is a little dangerous. There may be other examples, >>>>>>>but this is what I came up with in a about a minute. Still your rule is >>>>>>>promising. >>>>>>> >>>>>>>There are some positions your rule does not give as drawn, but "my" rule does. >>>>>>>The reverse is also true of course, so maybe the rules should be combined? >>>>>> >>>>>>I agree that the rules can be combined. >>>>>> >>>>>>Uri >>>> >>>> >>>> >>>>This discussion is very interesting. So what's the ultimate rule? >>>> >>>>I had to work on this recently in Chess Tiger (and Gambit Tiger of course), and >>>>I'm not sure my own rule is as good as yours. >>>> >>>>Waiting eagerly for the next post... >>>> >>>> >>>> >>>> Christophe >>> >>>The logic behind my rule is simple >>> >>>If black king is closer to the corner than the white king and the white pawn >>>nothing can stop it if it begins a trip to the corner. >>> >>>It can do the trip using squares that the bishop does not control and the other >>>pieces cannot see these squares. >>> >>>Uri >> >>I've been think about "the Blass ending rule" some more and it appears to be >>robust enough to handle the more general case. The cases where the superior side >>has more than one Bishop on the same color squares and/or more than one rook >>pawn on the same file. I can't think of a counter example. Can you? > >I agree. >If the defender side has only king my rule is correct. >I assume for the rest of the discussion that without loss of generalization the >defender is black and white has pawns only in the h file > >I believe that we can generalize also for cases when black has pawns but not on >the g file but we have to be careful to see that there are no black pawns in >black squares that are closer than the black king to the corner. > >We can evaluate the following positions as draws if we are not carful > >[D]8/8/5p2/4kB2/6KP/8/8/8 b - - 0 1 > >[D]8/4p3/4pp2/4kp2/5p2/5K2/7P/7B w - - 0 1 > > >Uri Well, when you add pawns to the inferior side, not even the rule I gave works: [D]7k/8/7K/3B4/6p1/7p/7P/8 w - - 0 1 1.Kg6 g3 2.hxg3 h2 3.g4 h1=Q 4.Bxh1 wins. It would complicate the rule quite a bit to accomodate the case where the inferior side has pawns. Also, the promised draw would only be a lower bound, since the "inferior" side might even be able to win.
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