Kleene's Three-Valued Logic

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This Demonstration presents a simple test for Kleene's three-valued logic. The values are: True, False, and Undefined (or Unknown or Undecided), with associated numerical values 1, 0, 1/2, respectively. The value of compound propositions is evaluated according to Kleene's truth tables.
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Contributed by: Izidor Hafner (March 2011)
Based on work by: Jon Barwise and John Etchemendy
Open content licensed under CC BY-NC-SA
Snapshots
Details
J. Barwise and J. Etchemendy, Tarski's World, Stanford, CA: CSLI Publications, 1993.
J. Barwise and J. Etchemendy, Hyperproof, Stanford, CA: CSLI Publications, 1994, pp. 11–13.
S. C. Kleene, Introduction to Matamathematics, New York: Elsevier, 1952, pp. 332–335.
Permanent Citation
"Kleene's Three-Valued Logic"
http://demonstrations.wolfram.com/KleenesThreeValuedLogic/
Wolfram Demonstrations Project
Published: March 7 2011