( ; AB [ne][od][of][pc][pd][pe][pf][pg][ph][qb][qc][qh][rc] AW [md][me][mf][nc][ng][ni][ob][oc][oj][pb][pj][qa][qd][qe][qf][qg][qj][rb][rh][rj][sa] ( ; B [rg]; W [rf] ( ; B [rd]; W [sg] ( ; B [re]; W [se] ( ; B [sb]; W [sc]; B [sd]; W [pa] ( ; B [sf]; W [rg] ( ; B [ri]; W [se] (; B [sb]; W [ra]; B [sf]; W [jb] TR[kb] C [Respond to the ko threat at the triangle if doing so does not cause your group to die.]; B [kb]; W [se]; B [qi]; W [si]; B [sf]; W [jc] TR [kc] C [Respond to the ko threat at the triangle if doing so does not cause your group to die.]; B [kc]; W [se]; B [sj]; W [sk]; B [sf]; W [jd] TR [kd] C [Respond to the ko threat at the triangle if doing so does not cause your group to die.]; B [sh]; W [kd] C [RIGHT][This is the ko that results from best play from black and one minor mistake by white. White needs black to respond to three ko threats to win the ko.]) (; B [qi]; W [si]; B [sf]; W [jb] TR[kb] C [Respond to the ko threat at the triangle if doing so does not cause your group to die.]; B [kb]; W [se] (; B [sb]; W [ra]; B [sf]; W [jc] TR [kc] C [Respond to the ko threat at the triangle if doing so does not cause your group to die.]; B [kc]; W [se]; B [sj]; W [sk]; B [sf]; W [jd] TR [kd] C [Respond to the ko threat at the triangle if doing so does not cause your group to die.]; B [sh]; W [kd] C [RIGHT][This is the ko that results from best play from black and one minor mistake by white. White needs black to respond to three ko threats to win the ko.])(; B [sj]; W [sk]; B [sf]; W [jc] TR [kc] C [Respond to the ko threat at the triangle if doing so does not cause your group to die.]; B [kc]; W [se]; B [sb]; W [ra]; B [sf]; W [jd] TR [kd] C [Respond to the ko threat at the triangle if doing so does not cause your group to die.]; B [sh]; W [kd] C [RIGHT][This is the ko that results from best play from black and one minor mistake by white. White needs black to respond to three ko threats to win the ko.])) (; B [si]; W [qi]; B [sf]; W [jb] TR[kb] C [Respond to the ko threat at the triangle if doing so does not cause your group to die.]; B [kb]; W [se]; B [sb]; W [ra]; B [sf]; W [jc] TR [kc] C [Respond to the ko threat at the triangle if doing so does not cause your group to die.] (; B [sh]; W [kc] C [White only needed to ko threats to win this ko. There is a better ko for black.])(; B [kc]; W [se] C [White wins the ko.])) ) (; B [sb]; W [ra] C [This wastes a ko threat.]) ) (; B [sb]; W [ra] C [This wastes a ko threat.]) ) (; B [sd]; W [sf]; B [sb]; W [sc] C [Not the best possible ko. White now needs only two outside ko threats to kill instead of three.]) (; B [pa]; W [oa] C [This wastes a ko threat; after optimal play, white now needs only two outside ko threats to kill instead of three.]) ) (; B [sc]; W [pa]) (; B [sd]; W [pa]) (; B [se]; W [sc]) (; B [pa]; W [oa] C [This wastes a ko threat; after optimal play, white now needs only two outside ko threats to kill instead of three.]) ) (; B [sc]; W [pa]) (; B [sd]; W [pa]) (; B [re]; W [rd]) (; B [se]; W [sg]) (; B [sg]; W [sh]) (; B [sf]; W [sg]) (; B [pa]; W [oa] C [This wastes a ko threat; after optimal play, white now needs only two outside ko threats to kill instead of three.]) ) (; B [sc]; W [pa]) (; B [sd]; W [pa]) (; B [ri]; W [rg]) (; B [rd]; W [rg]) (; B [re]; W [rg]) (; B [rf]; W [rg]) (; B [se]; W [rg]) (; B [sf]; W [rg]) (; B [sg]; W [rg]) (; B [pa]; W [oa] C [This wastes a ko threat; after optimal play, white now needs only two outside ko threats to kill instead of three.]) )