. , "" ("How?") " " ("Why?"). . , , . , . , , "How?". .
:
1) , , ;
2) , , .
, . , "<=" . , .
1. , .
2.
if Cond then P
:
<= ProofCond
ProofCond Cond.
3. , 1 2 ,
Proofl Proof2. ? is Fl and P2,
Proofl Proof2. is?1 or P2,
Proof 1 Proof2.
Prolog i st rue (. 15.4), . istrue 15.6. , , AND/OR. AND/OR. , , , 16.
, , . . -
II. Prolog
, . , "Why?", , . " " , , s 16.