context: It is probable that Greg is a rhino. Chances are about even that John went to the garden. It is highly likely that Jason is tired. There is almost no chance that if 'Greg is a rhino' or 'John went to the garden' or both then Julius is a lion. Chances are about even that if 'Greg is a rhino' or 'Jason is tired' or both then Daniel dropped the apple. There is a better than even chance that if 'John went to the garden' or 'Greg is a rhino' or both then Brian is a swan.
hypothesis: There is a very good chance that 'Greg is a rhino' or 'Daniel dropped the apple' or both.
valid_hypothesis: There is a very good chance that 'Greg is a rhino' or 'Daniel dropped the apple' or both.
invalid_hypothesis: There is little chance that 'Greg is a rhino' or 'Daniel dropped the apple' or both.
problog: 
    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.
    0.5::factB.
    0.9::factC.
    %hop1
    0.02::factX:-or(factA,factB).
    0.5::factY:-or(factA,factC).
    0.6::factZ:-or(factB,factA).
  
    %hop2
    conclusion:-or(factA,factY).
  
    query(conclusion).
    
hypothesis_assertion: 'Greg is a rhino' or 'Daniel dropped the apple' or both.