# The theme of this test suite is how to play inside an already living
# group to turn potential territory into a seki. A typical example
# would be this corner group
# where white can make seki in sente by playing at 'a'. There are also
# numerous test cases to check the followup moves to get a seki. In
# many cases one or both players have the option to make ko for life
# and death of the entire corner (whereby black would get territory
# points if winning). Is is generally assumed in this test suite that
# white tries to achieve ko while black tries to avoid it, since the
# ko in most cases is favorable to white.
# B2 also secures life but leaves a much bigger ko threat behind.
# Tenuki lets white make ko with A1
# White kills through bent four in the corner.
# C2 gives a sente seki, while B1 gives a gote seki. Other moves fail.
# Only B1 and A2 (oddly enough) avoids giving white a ko option.
# Both A2 and B1 lead to seki. Strictly speaking A2 is a better move
# since it leaves black the option to take sente and let white make a
# thousand-year ko. For now we accept both.
# White gets a thousand-year ko if black plays tenuki.
# A1 makes a clean seki with no ko aji.
# Black can start ko with B1 if desperate.
# Now black can live with territory.
# Tenuki is okay. What remains is a double-sided ko threat (0 points
# A2 also makes seki, but costs a prisoner.
# Most moves secure territory but C1 and C2 are most natural. We also
# C1 and C2 both secure seki in sente, but C1 is one prisoner better.
# B2 leaves white the option to make ko.
# D1 and A2 also give seki but are one point worse.
# D1 and A2 are miai to get seki. Black can also opt for a difficult
# ko by playing B2, but this is usually not a good idea. Tenuki
# suffices for seki and leaves a big mutual ko threat.
# B2 gives a hopeless ko.
# C2 is the best way to make seki since it leaves ko aji in black's
# favor unless white accepts gote.
# B1 also makes seki but white definitely ends in gote.
# After A2 black has the option to start ko with B1, unless white
# takes gote and fills at B1. Sooner or later that may be necessary.
# A2 is one point bigger than C1 regardless of scoring method.
# A3 is one point bigger than A2 under japanese scoring and a half
# point bigger under chinese scoring.
# B1 and A2 give gote seki.
# A2 is gote seki and may occasionally be better than allowing black
# A1 secures seki, removing white's ko aji.
# Black probably have more moves to make seki in sente but C2 looks most
# natural. C1 is also good enough. B1 suffices to make sente seki as well
# but loses one point compared to C2 or C1.
# B1 gives ko or seki in gote. Tenuki also leaves a seki but compared
# to C1 the latter is 1 point double sente.
# Black can play tenuki and still have seki but since A3 is one point
# double sente there is no reason to wait.
# 1 point double sente, just like 907.
# One point to pick up the A1 stone under Japanese rules.
# After white C1 black can make ko with A2 or seki in gote with D1.
# White C1 was a mistake. Black makes life with territory at B3.
# Black should play B2. A2 and B1 leave an unnecessary ko threat.
# Black can make seki in sente with most moves but B1 and A2 lose one
# point. Tenuki let's white kill with ko.
# B3, A2, and A1 fail to make seki.
# A3, B3, and A2 all make seki, but B3 and A2 lose a point.
# A3 gains a point compared to A2. B1 is two points worse.
# A3 gains a point compared to B3. B1 is two points worse.
# Tenuki leaves seki but loses a point.
# A2 also gives seki but loses a point, as does tenuki.
# B1 and B3 lose a point.
# Only A3 works. If black gets both C1 and A3, white can't do anything
# with two stones (in addition to B2).
# C1 is one point better than C2 and A3.
loadsgf games/FSGCBot-dr.sgf 234
loadsgf games/seki_nakade1.sgf
loadsgf games/seki_nakade2.sgf
projects / sgk-go / blob