Bottom Clause Construction

:- modeb(p(+a,+b,-c,#d)).

Registered term:

a(a1). a(a2). b(b1). b(b2).

Prolog goals

?- p(a1, b1, C1, D1).

?- p(a1, b2, C2, D2).

?- p(a2, b1, C3, D3).

?- p(a2, b2, C4, D4).

• Optimization by mode declaration

  • replace +type argument in each modeb declaration by constant (registered term ) relevant to example
  • replace -type and #type argument by variable
  • execute each modeb as Prolog goal.
  • If the goal success with ground substitutions then add it to the body of MSH

Select

rel0.att1, rel0.att2, rel0.att3, rel0.att4

From relationP rel0

Where

(rel0.att1=‘a1’ AND rel0.att2 = ‘b1’)OR

(rel0.att1=‘a1’ AND rel0.att2 = ‘b2’)OR

(rel0.att1=‘a2’ AND rel0.att2 = ‘b1’)OR

(rel0.att1=‘a2’ AND rel0.att2 = ‘b2’)

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