Note

The descendant filter has been deprecated. Use

  X≻Y

instead of

  descendant(X Y)

descendant (deprecated)

The descendant filter takes two position filters as arguments enclosed in parentheses. The descendant filter matches the position if the position represented by its first argument is a descendant of the position represented by its second argument.

   descendant(x y)

We say that position x is a descendant of position y if, starting from position y there is a nonempty sequence of moves from the PGN file that reach position x.

If x and y are mainline positions, then x is a descendant of y if and only if the position id of x is greater than the position id of y. Thus, in this case, one can test if x is a descendant of y simply by doing:

  x>y

Note that descendant(x y) is equivalent to ancestor(y x) .