Machine Intelligence 7 - AITopics

PROGRAM PROOF AND MANIPULATION
Si
I: =E
S2
where / is some identifier and E some expression, is said to be verified if
S1 FA [S2]f where [S2], means the statement S2 with E substituted for I
throughout. (This is called backward verification by King (1969); it is a
variant of Floyd's original method, which introduces an existentially quantified
variable.)
We will here retain the inductive method of Floyd for dealing with flow
diagrams containing loops, but give methods for coping with more complex
kinds of assignment command.
4. EXTENSION OF THE VERIFICATION PROCEDURE TO
ARRAY ASSIGN MENTS
Consider the following command and assertions
1‘,i< 9 and for all x, such that 1