K-Maps

I was reading about black-box testing when I came across a technique involving Karnaugh maps
(K-maps, or Veitch diagrams). These optimisation diagrams were invented by American mathematician Edward Veitch in 1952 and further refined by Maurice Karnaugh (BSc, Msc, PhD in Physics) at Bell Labs (now part of Alcatel-Lucent). In K-maps, boolean variables are taken (e.g. from a truth table) and ordered by Gray Code (aka reflected binary code) principles (where successive members of the code differ by only one digit).

Here is a software that creates K-Maps: http://www.sharewareplaza.com/images/screenshot/44948.gif