# power and powerdifference

The*power*of a piece is its material value: 1 for a pawn; 3 for a bishop or knight; 5 for a rook; and 9 for a queen. Kings and empty squares are ignored, or nominally have zero power.

The power of a set of squares in a position is the sum of the power of all the pieces on squares in that set in the position.

## power filter

The`power`

power filter is the word `power`

followed by a range followed by a set filter:
For example,power filter:= 'power'rangeset-filter

power 15 1000 Ais a power filter with range

`15 1000`

and set filter of `A.`

A power filter matches a position if the power of the pieces on the squares denoted by its set filter in that position lie within its range. Thus, `power 15 1000 A`

matches positions where the power (material value) of the White pieces is at least 15.

V. Kosek

1.p Slovensky Narod

1926

result 1-0 event "1.p" initial power 7 [Aa]

The diagram above shows the earliest first prize win study with an initial total power of 7.

## powerdifference

A*powerdifference filter*is the word

`powerdifference`

followed by a range and an argument list with two set filters:
A powerdifference filter matches a position if the difference in the powers of its first and second arguments lies within the range. For example:powerdifference:= 'powerdifference'range'('setfilter_{1}setfilter')'_{2}

T. Dawson

Schackvarlden

1945

result 1-0 wtm not check power 1 A powerdifference -1000 -20 (A a)The above study by Dawson has a powerdifference of 35.

Note that the

*range*can include negative values. Examples