It is probable that Mary went to the office. It is likely that John took the apple. There is a better than even chance that Julius is yellow. We doubt that if 'John took the apple' or 'Mary went to the office' or both then Bernhard is yellow. Chances are slight that if 'Julius is yellow and John took the apple' then Greg is a frog. It is likely that if 'Mary went to the office and John took the apple' then Sandra got the football.
There is almost no chance that 'Julius is yellow' or 'Sandra got the football' or both.
We believe that 'Julius is yellow' or 'Sandra got the football' or both.
There is almost no chance that 'Julius is yellow' or 'Sandra got 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
  0.7::factA.
  0.7::factB.
  0.6::factC.
  %hop1
  0.2::factX:-or(factB,factA).
  0.1::factY:-and(factC,factB).
  0.7::factZ:-and(factA,factB).

  %hop2
  conclusion:-or(factC,factZ).

  query(conclusion).
  
'Julius is yellow' or 'Sandra got the football' or both.