I'm having trouble interpreting this highlighted sentence (from Discrete Math Rosen Textbook) properly due to using unless more than once in this sentence. I understand that q unless (not p) is the same as saying p implies q, but I'm not sure how to exactly apply that rule here for this sentence. Is it equivalent to saying (by rearranging the sentence a bit):
Unless every input value is tested (call it proposition "p"), unless the correctness of the program is established (call it proposition "q"), no amount of testing can show it produces the desired output for all input values (call it proposition "r").
or
If every input value is not tested, then if the correctness of the program is not established, no amount of testing can show it produces the desired output for all input values.
or
(not p) --> ( (not q) --> r)
or
( (not p) and (not q) ) --> r
Kindly please help me here.
It might just be the commas throwing me off (my bad english lol)