Backtracking Families

• A backtracking family is a (multi) set of independent goals such that backtracking over one of them implies backtracking over all the others

• They do not need to belong to the same clause activation: the clause

  r:- p & q & r.

  generates the following goals:

  ...p & q & p & q & p & q & p & q & p & q...

• p's and q's instances can be executed in any order

• They can be backtracked in a shot

• No markers needed in between