[RESOLVED] Building Logical Statements

[selfishy_me]

I remember from one of my classes that there's a way to build logical statements using a chart. For example, the top row of the chart will contain something like 00 01 10 11 (I probably used the wrong order) and the same goes for the side row. Then we had to cross off boxes and circle them to make larger boxes, or a row of four boxes (or something along those lines). However, I don't remember what it is or the specifics. My notes are in a disarray and I've already sold my textbook. Does anyone know what this technique is called? And does anyone have bookmarked websites/articles on this technique?

[si_the_geek]

This sounds a bit (but not exaclty) like Truth Tables to me, eg:

A  B  | A and B
------|--------
0  0  |  0
0  1  |  0
1  0  |  0
1  1  |  1

..

[selfishy_me]

Sort of. It's based on truth tables but looks like this:



Unfortunately, the example I gave you is incorrect because I don't remember what order the numbers have to be in nor do I remember the rules for circling the dots. I would be indebted to the person who knows what this is lol.

[kfcSmitty]

Do you mean the old idea of doing
IE) for 4 bits

0000
0001
0010
0011
0100
0101
0110
0111
1000
1001
1010
1011
1100
1101
1110
1111

That?

Where to ensure you cover all posibilities in the truth table?

It goes half zeros, half 1's..then keep halving
IE) 8 zeros 8 ones Then
4 zeros 4 one 4 zeros 4 ones

etc

[selfishy_me]

It's ok. I found it. It took me two days to find it. *wipes brow*

It's called a Karnaugh Map or K-Map. It's a graphical way to represent truth values to create logical statements. You know how sometimes when you have really large truth tables, they can take up pages and pages of 0's, 1's, T's, and F's with all the wierd ^ V xor and stuff? Well, the Karnaugh Map simplifies it a bit and in the process, builds your logical statement.

Thanks kfc and si. You reminded me what I was doing when I learned the K-Map. We were programming simple circuit boards to light up some LEDs and we used the K-Map to build some complex logical statements because it was too complicated to write out all the binary combinations >.<

Oh, for anyone else who's interested, here's a link: http://www.ucsc.cmb.ac.lk/centre/elc...arnaughMap.htm

[Al42]

Boy, does that bring back memories. We were using Karnaugh maps to program some hardware in the late 60s-early 70s.