It is unlikely that Jason is bored. It is likely that Emily is a cat. We doubt that Mary went to the garden. It is unlikely that if 'Emily is a cat' or 'Jason is bored' or both then Brian is white. There is a very good chance that if either 'Emily is a cat' or 'Jason is bored' but not both then Greg is a lion. Chances are slight that if either 'Mary went to the garden' or 'Jason is bored' but not both then Julius is a swan.
There is a better than even chance that 'Mary went to the garden' or 'Greg is a lion' or both.
There is a better than even chance that 'Mary went to the garden' or 'Greg is a lion' or both.
It is impossible that 'Mary went to the garden' or 'Greg 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
  0.2::factA.
  0.7::factB.
  0.2::factC.
  %hop1
  0.2::factX:-or(factB,factA).
  0.8::factY:-xor(factB,factA).
  0.1::factZ:-xor(factC,factA).

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

  query(conclusion).
  
'Mary went to the garden' or 'Greg is a lion' or both.