Null moves gain

[geko]

how many ELOs does one gain using a version with null moves instead of one without?
thanks
g.

[Dann Corbit]

You gain a lot with null move. After change from mini-max to alpha-beta, this is the second most significant enhancement.
I guess 100 Elo, but it will depend on the engine.

It tends to be a bit fiddly to get it right, so examine some code from other engines (E.g. the make/unmake are slightly different, and the rules for when to do it and when not to do it are fiddly too).

Vincent's double null move rule is the easiest way to implement it and always stay out of trouble with it.