Next I analysed the 5x2 edge: this comes up (in my games at least)

more often than the 4x2 corner. Here's another one I would have

got wrong. Again, this one is perhaps too hard for a human to

solve completely rigorously, but I have always (recently at least)

been playing 5x2s

in a certain way and this puzzle shows (to me) that I've been doing it

wrong: again I would have lost 13-12 playing against a computer

from this position. Blue is three down but if the bottom region

forms a chain then it's his. How to play so as to win the game?

There are two winning moves and if anyone has played a game

against me where such a region has showed up, they might well

know how I play these positions, and the move I usually play

in those 5x2 regions to “maximise the chain” isn't the right one!

6 + + +-+-+-+      |r|b|b|5 +-+-+-+-+-+  |r|r|r|b|b|4 +-+-+-+-+-+  |r|r|r|r|b|3 +-+-+-+-+-+             2 + + + + + +             1 + + + + + +  a b c d e f

wcc