Re: [gnugo-devel] look at regress file 13x13b:6

[kevin yong]

Hi, Evan:

  i did more work on 13x13b:6. here are what i got:

  1. where/how/why B3 was found to be a save move for
dragon B6:

  call sequence:

    do_genmove()
      examine_position()
        make_dragons()
          owl_defend()
            do_owl_defend()
              owl_estimate_life()
              do_owl_attack()
                owl_estimate_life()
              ... indirect recursive call
defend/attack

  each time before call attack/defend, it
estimate_life first.
  i made some print to see do_owl_defend/do_owl_attack
works:

do_owl_defend B6 with B3 
  do_owl_attack on B6 with B4
    do_owl_defend B6 with C3 
      owl_estimate_life return TRUE, 2 or more secure
        eyes 
      do_owl_defend success on B6 with C3 
  do_owl_attack on B6 with C4
    do_owl_defend B6 with C3 
      do_owl_attack on B6 with B4
        do_owl_defend B6 with D2 
          owl_estimate_life return TRUE, 2 or more 
            secure eyes 
        do_owl_defend success on B6 with D2 
      do_owl_defend success on B6 with C3 
  do_owl_defend success on B6 with B3 

  This is the my interpretation:
  W move at B3 to defend B6;
    B check dragon life, false;
    B move at B4 to attack B6;
      W check dragon life, false;
      W move at C3 to defend B6;
        B check dragon life, TRUE !!! (this is wrong)
        so, no more attack
      W claim success to answer B attack at B4.
    (next)
    B move at C4 to attack B6;
      W check dragon life, false;
      W move at C3 to defend B6;
        B check dragon life, false;
        B move at B4 to attack B6;
          W check dragon life, false;
          W move at D2 to defend B6;
            B check dragon life, TRUE !!!(wrong again)
            so, no more attack
      W claim success to answer B attack at C4.
    finally, W claim success to defend B6 with B3.

  there are several issues here:
    issue a: i have not fully understand
owl_estimate_life() works: it does NOT take any dragon
origin as input, but it take loca_owl_data as input,
inside which, has owl->goals[] array, which suppose to
contain the stones of the dragon (that's my
understanding, corret me if i m wrong). but, when the
dragon asserted to be alive by owl_estimate_life(), i
print out what's inside owl->goals[]. for dragon B6,
here is what i got:
      J7
      B6
      H6
      J6
      K6
      A5
      B5
      E5
      F5
      G5
      J5
      K5
      D4
      K4
      L4
      B3
      C3
      F3
      M3
      F2
      H2
      L2
      M2
      J1
      K1
  if you know more about this, please give me some
indication about this.

  issue b: at the second move, B move at B4/C4 to
attack, W answered both with move C3, which is out of
reach to save B6.

  2. recommandation: some improvement on owl.c

  thank you in advance.

kevin.




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