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Source Code for FAMILY Example

DATABASE - tmp
  son(STRING,STRING)
  sister(STRING,STRING)
  brother(STRING,STRING)
  married(STRING,STRING)

CLAUSES
  son("John", "Dan").
  sister("Mary","Suzan").
  brother("Harold", "Larry").
  married("John", "Mary").
  married("Larry", "Sue").

PREDICATES
  father(STRING father,STRING child)
  grandfather(STRING grandfather,STRING grandchild)
  sister_in_law(STRING,STRING)

CLAUSES
  father(A,B):-son(B,A).

  grandfather(A,B):-father(A,C), father(C,B).

  sister_in_law(A,B):-married(A,C), sister(C,B).
  sister_in_law(A,B):-brother(A,C), married(C,B).

GOAL sister_in_law("John",Z).