Example: Strict Goal Independence

• Def: Goals are strictly independent iff they do not share variables at run-time.

• Parallel execution of strictly independent goals: same solution as with standard sequential execution (+ better finite failure behavior).

• Can still be speculative:
  X=b, , p(X), q(X),
  p(X) :- ..., X=a, ...
  q(X) :- large computation.

  
  
  
  but ``no slow-down'' guaranteed if

  • left-biased scheduling,
  • instantaneous killing of siblings (failure propagation).

• Non-failure: avoids speculativeness (guarantees theoretical speedup) importance of non-failure analysis.

• Compile-time generation of run-time tests: