It is highly likely that Fred discarded the apple. It is highly unlikely that Mary dropped the apple. It is likely that Greg is yellow. There is a very good chance that if 'Greg is yellow' or 'Fred discarded the apple' or both then Sandra put down the milk. We believe that if 'Greg is yellow' or 'Mary dropped the apple' or both then Julius is a frog. There is little chance that if 'Fred discarded the apple and Mary dropped the apple' then Brian is yellow.
Chances are about even that 'Julius is a frog and Fred discarded the apple'.
Chances are about even that 'Julius is a frog and Fred discarded the apple'.
It is certain that 'Julius is a frog and Fred discarded the apple'.

  and(A,B) :- A,B.
  or(A,B) :- A;B.
  nand(A,B) :- not(and(A,B)).
  nor(A,B) :- not(or(A,B)).
  xor(A,B) :- or(A,B), nand(A,B).

  %hop0
  0.9::factA.
  0.05::factB.
  0.7::factC.
  %hop1
  0.8::factX:-or(factC,factA).
  0.75::factY:-or(factC,factB).
  0.1::factZ:-and(factA,factB).

  %hop2
  conclusion:-and(factY,factA).

  query(conclusion).
  
'Julius is a frog and Fred discarded the apple'.