It is likely that Bernhard is green. It is probable that John discarded the apple. We doubt that Jason is tired. There is a better than even chance that if 'John discarded the apple' or 'Jason is tired' or both then Mary went to the office. It is unlikely that if 'Bernhard is green' or 'Jason is tired' or both then Brian is a lion. There is little chance that if 'John discarded the apple and Jason is tired' then Greg is a swan.
There is little chance that 'Bernhard is green' or 'Brian is a lion' or both.
It is probably the case that 'Bernhard is green' or 'Brian is a lion' or both.
There is little chance that 'Bernhard is green' or 'Brian is a lion' or both.

  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
  0.7::factA.
  0.7::factB.
  0.2::factC.
  %hop1
  0.6::factX:-or(factB,factC).
  0.2::factY:-or(factA,factC).
  0.1::factZ:-and(factB,factC).

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

  query(conclusion).
  
'Bernhard is green' or 'Brian is a lion' or both.