It is highly unlikely that Bernhard is a rhino. It is highly likely that Lily is a lion. It is improbable that Brian is a frog. It is probable that if 'Bernhard is a rhino' or 'Brian is a frog' or both then Greg is a swan. It is certain that if either 'Lily is a lion' or 'Bernhard is a rhino' but not both then Sandra dropped the milk. It is highly likely that if either 'Brian is a frog' or 'Bernhard is a rhino' but not both then Mary went to the hallway.
It is unlikely that 'Mary went to the hallway' or 'Lily is a lion' or both.
It is highly likely that 'Mary went to the hallway' or 'Lily is a lion' or both.
It is unlikely that 'Mary went to the hallway' or 'Lily 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
  0.05::factA.
  0.9::factB.
  0.1::factC.
  %hop1
  0.7::factX:-or(factA,factC).
  1.0::factY:-xor(factB,factA).
  0.9::factZ:-xor(factC,factA).

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

  query(conclusion).
  
'Mary went to the hallway' or 'Lily is a lion' or both.