DHowell.ElSegundo@Xerox.COM (08/20/87)
In article <3696@ecsvax.UUCP>, uccjcm@ecsvax.uucp (Jonathon C. McLendon IV) writes: >Apply the contra-positive to the statement "Not looking like Pascal implies >not a language deficiency." One obtains "A language deficiency implies >looking like Pascal" which is not "Looking like Pascal implies a language >deficiency." These are the proper reduced statements, and they are not >equivalent. The original statement was "not looking like Pascal is not a language deficiency". This is obviously not equivalent to "A language deficiency implies looking like Pascal", using COBOL as an example which defies this statement but not the original one. (COBOL is deficient but does not look like Pascal.) Errors are being made with regards to the meaning of "is not". Some people are saing that it means "implies not" and others say it means "does not imply". While the second interpretation is closer to the truth, the real meaning of "is not" in this case is "is not a sufficient condition." The original statement is the complement of the statement "not looking like Pascal is a language deficiency". This complement means that not looking like Pascal is a sufficient condition for a language to be deficient. (Which also would mean that looking like Pascal is a necessary condition for a non-deficient language.) Thus the original statement means that not looking like Pascal is NOT a sufficient condition for a language to be deficient. (Or, looking like Pascal is not a necessary condition for a non-deficient language.) All this means is that there exists a language which does not look like Pascal and is not deficient. This IS the reduced statement (in English instead of LISP :-) "Looking like Pascal is a language deficiency" means that looking like Pascal is a sufficient condition for a deficient language. This means that there does not exist a language which looks like Pascal and is not deficient. Clearly a different statement than the other one. "Not looking like Pascal implies not a language deficiency" means that not looking like Pascal is a sufficient condition for a non-deficient language. This means that there does not exist a languae which does not looks like pascal and is deficient. A different statement than either of the other two. So hopefully I've settled all this and we can get back to talking about pointers to unspecified size arrays and gotos and switches and other relevant topics. >Now, this is really not a proper subject for comp.lang.c, so I will have >no further responses. All flamage, slammage, damage to /dev/null please. /dev/null: write error, device full. Sending to comp.lang.c... Dan <DHowell.ElSegundo@Xerox.COM> DISCLAIMER: "I'm right, so who cares what my employer thinks? :-)"