There is little chance that Brian is a rhino. It is unlikely that Gertrude is a mouse. There is almost no chance that Emily is a cat. It is probable that if either 'Gertrude is a mouse' or 'Emily is a cat' but not both then Mary moved to the office. It is probably the case that if 'Gertrude is a mouse and Emily is a cat' then Greg is white. It is probably not the case that if 'Gertrude is a mouse and Emily is a cat' then Daniel grabbed the apple.
Chances are about even that 'Greg is white and Gertrude is a mouse'.
It is impossible that 'Greg is white and Gertrude is a mouse'.
Chances are about even that 'Greg is white and Gertrude is a mouse'.

  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
  0.1::factA.
  0.2::factB.
  0.02::factC.
  %hop1
  0.7::factX:-xor(factB,factC).
  0.7::factY:-and(factB,factC).
  0.25::factZ:-and(factB,factC).

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

  query(conclusion).
  
'Greg is white and Gertrude is a mouse'.