Chances are about even that Fred moved to the office. There is little chance that Antoine is thirsty. It is probable that Yann is bored. It is unlikely that if either 'Yann is bored' or 'Antoine is thirsty' but not both then Mary left the football. It is highly unlikely that if 'Antoine is thirsty' or 'Fred moved to the office' or both then Julius is a lion. It is improbable that if 'Fred moved to the office and Yann is bored' then John grabbed the apple.
It is probably the case that 'Mary left the football' or 'Antoine is thirsty' or both.
It is probably not the case that 'Mary left the football' or 'Antoine is thirsty' or both.
It is probably the case that 'Mary left the football' or 'Antoine is thirsty' 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
  0.5::factA.
  0.1::factB.
  0.7::factC.
  %hop1
  0.2::factX:-xor(factC,factB).
  0.05::factY:-or(factB,factA).
  0.1::factZ:-and(factA,factC).

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

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