prolog-paren-indent

prolog-paren-indent is a variable defined in `prolog.el'.
Its value is

4

Documentation:
The indentation increase for parenthesis expressions.
Only used in ( If -> Then ; Else) and ( Disj1 ; Disj2 ) style expressions.

You can customize this variable.

This variable was introduced, or its default value was changed, in version 24.1 of Emacs.