There is a very good chance that Greg is a frog. It is probably the case that Jason is thirsty. It is highly unlikely that John discarded the apple. It is highly unlikely that if 'Greg is a frog' or 'Jason is thirsty' or both then Bernhard is a swan. It is probable that if either 'John discarded the apple' or 'Jason is thirsty' but not both then Mary left the football. There is little chance that if 'John discarded the apple and Jason is thirsty' then Brian is a lion.
There is little chance that 'Jason is thirsty' or 'Mary left the football' or both.
It is likely that 'Jason is thirsty' or 'Mary left the football' or both.
There is little chance that 'Jason is thirsty' or 'Mary left the football' 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
  0.8::factA.
  0.7::factB.
  0.05::factC.
  %hop1
  0.05::factX:-or(factA,factB).
  0.7::factY:-xor(factC,factB).
  0.1::factZ:-and(factC,factB).

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

  query(conclusion).
  
'Jason is thirsty' or 'Mary left the football' or both.