context: There is little chance that Mary went to the office. There is a very good chance that Sumit is tired. Chances are slight that John dropped the apple. It is certain that if 'Sumit is tired and John dropped the apple' then Sandra left the milk. There is almost no chance that if either 'John dropped the apple' or 'Sumit is tired' but not both then Greg is gray. It is improbable that if 'Mary went to the office and Sumit is tired' then Brian is a swan.
hypothesis: It is likely that 'John dropped the apple and Mary went to the office'.
valid_hypothesis: There is almost no chance that 'John dropped the apple and Mary went to the office'.
invalid_hypothesis: It is likely that 'John dropped the apple and Mary went to the office'.
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
    0.1::factA.
    0.8::factB.
    0.1::factC.
    %hop1
    1.0::factX:-and(factB,factC).
    0.02::factY:-xor(factC,factB).
    0.1::factZ:-and(factA,factB).
  
    %hop2
    conclusion:-and(factC,factA).
  
    query(conclusion).
    
hypothesis_assertion: 'John dropped the apple and Mary went to the office'.