Comments on: Swapping the values of two variables http://www.joaoff.com/2007/07/11/swapping-the-values-of-two-variables/ Programming, Algorithms, and Mathematics Tue, 06 Jan 2009 15:34:22 +0000 http://wordpress.org/?v=2.6.1 By: jff http://www.joaoff.com/2007/07/11/swapping-the-values-of-two-variables/#comment-52 jff Wed, 11 Jul 2007 21:16:35 +0000 http://www.joaoferreira.org/2007/07/11/swapping-the-values-of-two-variables/#comment-52 sdv: truth tables correspond to case analysis, and case analysis is usually used when we can't recognize the structure of the problem. Therefore, it should be avoided (in fact, its avoidance is one of the basic rules of the effective problem solver). Note that using truth tables you can prove the validity of a logical formula, but if that formula contains N variables, you have to consider 2^N different cases. It is much more simple to use algebraic properties of the logical operations. sdv: truth tables correspond to case analysis, and case analysis is usually used when we can’t recognize the structure of the problem. Therefore, it should be avoided (in fact, its avoidance is one of the basic rules of the effective problem solver).

Note that using truth tables you can prove the validity of a logical formula, but if that formula contains N variables, you have to consider 2^N different cases. It is much more simple to use algebraic properties of the logical operations.

]]> By: sdv http://www.joaoff.com/2007/07/11/swapping-the-values-of-two-variables/#comment-51 sdv Wed, 11 Jul 2007 20:54:08 +0000 http://www.joaoferreira.org/2007/07/11/swapping-the-values-of-two-variables/#comment-51 I'm impressed! If you find any example instantiation, be it nice or not, let us know. P.S. from programming.reddit.com: "The thing is that, usually, the bitwise trick is presented using truth tables (ergh!)." So, the truth tables push your buttons :) I’m impressed! If you find any example instantiation, be it nice or not, let us know.

P.S.
from programming.reddit.com:
“The thing is that, usually, the bitwise trick is presented using truth tables (ergh!).”
So, the truth tables push your buttons :)

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