RE Bad terms in seq A108719? (last one)

Tautócrona tautocrona at
Wed Nov 16 01:04:38 CET 2005

----- Original Message ----- 
From: "Tautócrona" <tautocrona at>

The flaw is, of course, in 5.). If we have that q --> -p then we know that Q is a subset
of -P, not the other way around. So we can not infer from q --> -p and p & q that we have
p & -p because P & Q is a set smaller than P & -P (I hope the logic-set theory analogy is
clear for anyone). I applied a false modus.

Oops! Forget (and forgive) entirely my last thread. I must have been lobotomyzed or 

Obviously if we have q, and we have q --> -p, then we have -p. This' real basic logic. The 
flaw was in 4., we can say that there's "at least one element that..." in the empty set. I 
was confunded by an intuitive pseudo-analogy I thought was right between formal logic and 
set theory.

Regards. Jose Brox 

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