How much to reduce ?

[Laszlo Gaspar]

Hi,

I use a table for nullmove reduction (nulldepth = table[depth]) so I can experiment on each depth separatly. My table is like this: [-1, -1, -1, 0, 0, 1, ...] (-1 means calling QS). I have gain from the nullmove test even at depth==0 where R==0 and call QS. At depth 3 R==2 and at depth 4 R==3 this way. Others might find other values better one for their programs of course. I use a small trick for nullmove: I first test with R==depth, which means I call QS first for a quick test. If I get a fail-low immediately then I don't do an expensive null move test.
For LMR R==1 works well, but don't reduce tactical moves. I reduce from the 5th move.
Hope this helps!