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How to implement KPK ?
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H.G.Muller



Joined: 10 Mar 2006
Posts: 21293
Location: Amsterdam

PostPost subject: Re: How to implement KPK ?    Posted: Thu Mar 21, 2013 10:33 am Reply to topic Reply with quote

The white pass and black pass look very similar, so perhaps it is more elegant to merge them into one routine:

Code:
void
Pass (int stm)
{
  int wk, bk, p, d;
  for(wk=0; wk<64; wk++) for(bk=0; bk<64; bk++) for(p=0; p<64; p++) {
    int k = stm == WTM ? wk : bk
    int O88 = (k & 070) + k; // 0x88 square number of King
    if(dtc[stm][wk][p][bk]) continue; // already decided
    dtc[stm][wk][p][bk] = stm;  // assume lost if btm, undecided if wtm
    if(bk != p && stm == WTM) { // pawn not captured, so can move
      if(p+8 != bk && dtc[BTM][wk][p+8][bk] > 0)  { dtc[WTM][wk][p][bk] = 1; continue; }
      if(p+7 == bk && (p & 7) != 0)  { dtc[WTM][wk][p][bk] = 1; continue; }
      if(p+9 == bk && (p & 7) != 7)  { dtc[WTM][wk][p][bk] = 1; continue; }
    }
    for(d=0; d<8; d++) {
      int to = O88 + steps[d];
      if(to & 0x88) continue; // off board
      if(stm == WTM ? dtc[BTM][to][p][bk] > 0 : dtc[WTM][wk][p][to] > 0)
      { dtc[stm][wk][p][bk] = !stm; break; }
    }
  }
}

void
Build ()
{
  int i;
  Init();
  for(i=0; i<100; i++) // won't take more than 100 moves
    Pass(WTM), Pass(BTM);
  Pack();
}


I guess the bk == p positions should be set to -1 in Init(), and not to 1; the Pass() code does not ever test the state of the daughter position in dtc when it captures the black King with a Pawn, but just assigns a win. So the only testing of this position that ever is important is when the black King stepped onto the Pawn, whether on the previous ply or longer before that. The btm cases have to be marked as draw, to prevent black being forced to 'step off' the Pawn again by zugzwang when white does not have a King move to capture the black King, and tries another one.
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Subject Author Date/Time
How to implement KPK ? Chan Rasjid Thu Mar 21, 2013 3:43 am
      Re: How to implement KPK ? H.G.Muller Thu Mar 21, 2013 7:46 am
            Re: How to implement KPK ? Chan Rasjid Thu Mar 21, 2013 8:27 am
                  Re: How to implement KPK ? H.G.Muller Thu Mar 21, 2013 10:07 am
                        Re: How to implement KPK ? H.G.Muller Thu Mar 21, 2013 10:33 am
                        Re: How to implement KPK ? Chan Rasjid Thu Mar 21, 2013 6:10 pm
                              Re: How to implement KPK ? Don Dailey Tue Apr 02, 2013 6:56 pm
            Re: How to implement KPK ? Lucas Braesch Thu Mar 21, 2013 11:03 am
                  Re: How to implement KPK ? H.G.Muller Thu Mar 21, 2013 11:52 am
                        Re: How to implement KPK ? Lucas Braesch Thu Mar 21, 2013 12:04 pm
                        Re: How to implement KPK ? H.G.Muller Thu Mar 21, 2013 6:36 pm
                              Re: How to implement KPK ? H.G.Muller Thu Mar 21, 2013 9:00 pm
                              Re: How to implement KPK ? Chan Rasjid Sat Mar 30, 2013 8:15 am
                                    Re: How to implement KPK ? Evert Glebbeek Sat Mar 30, 2013 8:42 am
                                          Re: How to implement KPK ? Sven Schüle Sat Mar 30, 2013 12:12 pm
                                                Re: How to implement KPK ? Chan Rasjid Sat Mar 30, 2013 12:20 pm
                                                      Re: How to implement KPK ? Sven Schüle Sat Mar 30, 2013 12:42 pm
                                                            Re: How to implement KPK ? Chan Rasjid Sat Mar 30, 2013 2:03 pm
                                                                  Re: How to implement KPK ? Sven Schüle Sat Mar 30, 2013 6:29 pm
                                                      Re: How to implement KPK ? Wylie Garvin Sat Mar 30, 2013 12:50 pm
                                                            Re: How to implement KPK ? Chan Rasjid Sat Mar 30, 2013 1:53 pm
                                                Re: How to implement KPK ? Evert Glebbeek Sat Mar 30, 2013 2:03 pm
                                                      Re: How to implement KPK ? H.G.Muller Sat Mar 30, 2013 2:26 pm
                                                            Re: How to implement KPK ? Sven Schüle Sat Mar 30, 2013 6:38 pm
                                                                  Re: How to implement KPK ? H.G.Muller Sat Mar 30, 2013 8:13 pm
                                                                        Re: How to implement KPK ? Sven Schüle Sat Mar 30, 2013 8:58 pm
                                                                              Re: How to implement KPK ? H.G.Muller Sat Mar 30, 2013 10:58 pm
                                                                                    Re: How to implement KPK ? Sven Schüle Sat Mar 30, 2013 11:51 pm
                                                                                          Re: How to implement KPK ? H.G.Muller Sun Mar 31, 2013 7:35 am
                                                                                          Re: How to implement KPK ? Sven Schüle Sun Mar 31, 2013 9:02 am
                                                                                          Re: How to implement KPK ? H.G.Muller Sun Mar 31, 2013 9:09 am
                                                                                          Re: How to implement KPK ? Sven Schüle Sun Mar 31, 2013 9:13 am
                                                                                          Re: How to implement KPK ? Steven Edwards Mon May 13, 2013 2:14 am
                                                                                          Re: How to implement KPK ? Don Dailey Mon May 13, 2013 2:20 am
                                          Re: How to implement KPK ? Chan Rasjid Sat Mar 30, 2013 12:18 pm
                                    Re: How to implement KPK ? H.G.Muller Sat Mar 30, 2013 9:08 am
      Re: How to implement KPK ? Chan Rasjid Sun May 12, 2013 10:27 pm
            Re: How to implement KPK ? Ronald de Man Sun May 12, 2013 11:11 pm
                  Re: How to implement KPK ? Chan Rasjid Mon May 13, 2013 7:39 am
            Re: How to implement KPK ? Don Dailey Mon May 13, 2013 2:14 am
            Re: How to implement KPK ? Steven Edwards Tue May 14, 2013 7:19 am
                  Re: How to implement KPK ? Chan Rasjid Tue May 14, 2013 2:45 pm
                        Re: How to implement KPK ? Chan Rasjid Tue May 14, 2013 2:50 pm
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