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:

      power filter := 'power' range set-filter

For example,

      power 15 1000 A

is 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:

      powerdifference := 'powerdifference' range '(' setfilter1 setfilter2 ')'

A powerdifference filter matches a position if the difference in the powers of its first and second arguments lies within the range. For example:

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