Examples of this include the analysis of zugzwang (a situation in chess or other games in which a null move, if it were allowed, would be better than any other move),[1] and the null-move heuristic in game tree analysis (a method of pruning game trees involving making a null move and then searching to a lower depth).
[2] The reason a reduced-depth null move is effective in game tree alpha-beta search reduction is that tactical threats tend to show up very quickly, in just one or two moves.
Even if the null move search value doesn't exceed beta, the returned value may set a higher floor on the valuation of the position than the present alpha, so more cutoffs will occur at descendant sibling nodes from the position.
Therefore it is necessary to have logic to exclude null moves at nodes in the tree where zugzwang is possible.
In chess, zugzwang positions can occur in king and pawn endgames, and sometimes in end games that include other pieces as well.