In the topic "What are the worst mistakes" I hinted at a heuristic I have discovered - at least for myself, calling it a "proverb" would be presumptuous - defend while making territory. In close association to that I dare suggesting another one:
Here's the position at move 120 in the 1d-2d game I talked about in the same topic.
White has played
as a reduction. AI Sensei calls it a decent move, still an inaccuracy of -2.5 pts (which is however not sustained in subsequent analysis, i.e. it's probably a better move than AI Sensei computes in my basic version)Let's assess territories first, using multiples of 5
Upper left: a white corner which might still be invaded or reduced by a lot, depending on Black's strength; let's estimate it conservatively at 5
Upper side: a stable 10 point territory for White
Upper right: a stable 5 point corner for Black
Right side: a stable 15 point territory for White
Lower right: a 40 point corner for Black, including the 4 captured stones, which induce some aji (see below)
Lower left: a stable 15 point corner for White
Left side: depends on Black's response; if passive defense it's a 15 point territory; l
Let's count 5 points komi for White
Both have a somewhat floating group in the center: Black's dragon on the upper side and White's group on the lower side.
Let's not count any points for them yet. Let's not discount anything either, for they're not weak. Black's has some eye shape and has moved out towards friendly stones. White has an eye at A in sente and central influence
This puts Black +10 which is indeed AI Sensei's score estimation.
Obviously
is looking for a way to disrupt Black's advantage by also aiming at a separating move around B, while also helping her own group. It's a multi-purpose move.Now, how do you assess this situation? I'll discuss the proceedings and my newfound heuristics in later posts.
at b to help the upper group while attacking 
to defend the left side with 
then 
and 
have made endgame profit against Black's stones becoming neutral.
in katrain. To me this looks like a brewing double attack but it might be risky if black is clearly ahead, which is what was claimed.
save the day?
and 
so Black loses tempo here.