# Kyoto2.org

Tricks and tips for everyone

# How does null move pruning work?

## How does null move pruning work?

also called Null Move Heuristic (NMH), is a method based on the Null Move Observation to reduce the search space by trying a “null” or “passing” move, then seeing if the score of the subtree search is still high enough to cause a beta cutoff.

How do you implement null moving pruning?

Thus, the best way to apply null-move pruning is by conducting a minimal-window null-move search around the current upper bound β, since such a search will require a reduced search effort to determine a cutoff. A typical null-move pruning implementation is given by the pseudo-code of Figure 1.

### What is null move in chess?

Often a null move is a placeholder in a pgn file to attach comments to regarding a position. It is denoted by “–” in PGN notation and internally represents a move by the king to it’s own square. As such it is an illegal move but as a vehicle for annotation it is extremely useful.

What is meant by heuristic algorithm?

A heuristic algorithm is one that is designed to solve a problem in a faster and more efficient fashion than traditional methods by sacrificing optimality, accuracy, precision, or completeness for speed. Heuristic algorithms often times used to solve NP-complete problems, a class of decision problems.

#### What is heuristic function?

Definition. A heuristic function (algorithm) or simply a heuristic is a shortcut to solving a problem when there are no exact solutions for it or the time to obtain the solution is too long.

What is null in games?

In game theory, a null move or pass is a decision by a player to not make a move when it is that player’s turn to move. Even though null moves are against the rules of many games, they are often useful to consider when analyzing these games.

## Which node will be pruned first?

Following are some rules to find good ordering in alpha-beta pruning: Occur the best move from the shallowest node. Order the nodes in the tree such that the best nodes are checked first. Use domain knowledge while finding the best move.

What is an example of A heuristic?

Heuristics can be thought of as general cognitive frameworks humans rely on regularly to quickly reach a solution. For example, if a student needed to decide what subject she will study at university, her intuition will likely be drawn toward the path that she envisions most satisfying, practical and interesting.