Question
Asked 28 September 2015

Is there a general form to determine if a tautology in classical propositional logic is a tautology in Lukasiewicz propositional logic?

Lukasiewicz propositional logic L_n takes truth values from the set {0, 1/(n-1), ..., (n-2)/(n-1), 1}. The propositional conectives are defined as a generalization of the classical. Any tautology in L_n is a classical tautology. The converse is false. Only some tautologies in L_n are classical tautologies, but how to know which classical tautologies are tautologies in L_n? Is this possible?

Popular answers (1)

François Schwarzentruber
Ecole normale supérieure de Rennes
Dear Carlos Pabón Chipatecua,
You say that Lukasiewicz propositional logic L_n takes truth values from the set {0, 1/(n-1), ..., (n-2)/(n-1), 1}.
It means that L_n is a logic where atomic propositions take truth values from a finite set of values. Also, the truth tables for the connectives are finite tables of size n X n.
Let phi a propositional formula. You can build a formula tr(phi) such that
phi is L_n-valid iff tr(phi) is valid in classical propositional logic
The translation tr is tedious to write down but is polynomial in the size of phi. As a proposition p takes n possible values, you can encode your value by log n + 1 binary digits p_0, ...p_{log n}. You also encode the truth tables via propositions p_0, ... p_{log n}.
You can actually write a program that performs the translation. Then, in order to know whether phi is L_n-valid, you test whether tr(phi) is valid. This can be done systematically by calling a SAT solver on not tr(phi).
Have a nice day.
Best,
François
3 Recommendations

All Answers (3)

Víctor S Albis
National University of Colombia
Ask Xavier Caicedo or Andres Villaveces
François Schwarzentruber
Ecole normale supérieure de Rennes
Dear Carlos Pabón Chipatecua,
You say that Lukasiewicz propositional logic L_n takes truth values from the set {0, 1/(n-1), ..., (n-2)/(n-1), 1}.
It means that L_n is a logic where atomic propositions take truth values from a finite set of values. Also, the truth tables for the connectives are finite tables of size n X n.
Let phi a propositional formula. You can build a formula tr(phi) such that
phi is L_n-valid iff tr(phi) is valid in classical propositional logic
The translation tr is tedious to write down but is polynomial in the size of phi. As a proposition p takes n possible values, you can encode your value by log n + 1 binary digits p_0, ...p_{log n}. You also encode the truth tables via propositions p_0, ... p_{log n}.
You can actually write a program that performs the translation. Then, in order to know whether phi is L_n-valid, you test whether tr(phi) is valid. This can be done systematically by calling a SAT solver on not tr(phi).
Have a nice day.
Best,
François
3 Recommendations

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How is it possible to force research community to validate proof for heretical Truth/Facts, if the Truths can usher in a technological revolution?
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  • Raju ChiluvuriRaju Chiluvuri
Dear Friends,
Isn’t it wrong to snub, sabotage and/or refuse to verify a heretical truth (if skeptical or suspicious) when the truth is not hard to verify, where a heretical Truth imply that it is a fact that challenges conventional wisdom and is perceived to be heresy (in the context of prevailing dominant paradigm), and the Truth can be proved to be a fact beyond any reasonable doubt by preponderance of evidence, reasoning and observable facts.
For example, assume that it is possible to subvert a dominant paradigm by proving the verifiable fact “234567*765432 = 179,545,087,944” (I.e. multiplication of 234567 with 765432 is equals 179,545,087,944). It may be bit harder to verify this fact manually without a calculator, but not impossible to verify the fact. Is it ethical to snub, sabotage and/or refuse to verify such a heretical fact, when the fact is not hard to verify?
It is extremely painful, if large number of brilliant researchers are incapable of understanding (or pretend to be incapable of understanding) simple logical facts. What else I can do, if experts refuse to verify (or incapable of verify) simple verifiable facts (e.g. 567*765 = 433,755), in addition to offering to face criminal prosecution, if I am wrong.
My whole proof/argument rests on 2 simple verifiable objective logical facts, which are:
(2) The core/root cause for, why dominant paradigm for any scientific or technological discipline inevitably and certainly ends up as a fake science (i.e. the geocentric paradox of the discipline filled with inexplicable epicycles and retrograde motions): http://real-software-components.com/raju/ModifiedKuhnBlackHolePhase.pdf (Kindly refer to the figure in 1st page and description for the figure in 2nd page).
Kindly understand and don’t forget that it is gross negligence, if researchers at taxpayer funded research organizations continue to ignore, snub or sabotage such logical facts. Such gross, if not criminal negligence, certainly would continue to cost trillions of dollars to the global economy and likely cost many more lives in the future: http://real-software-components.com/raju/SoftwareApocalypse2.pdf
Other costs include irreparable harm to (i) the creative possibilities and/or outcomes of countless research efforts in the right path of brilliant young researchers, and (ii) productivity, and creative possibilities of millions impressionable students (e.g. who will be either future researchers of computer science, or practitioners of craft of software engineering), who are being indoctrinated (by academic institutions around the world) into the geocentric paradoxes of computer science and software engineering disciplines.
I am helpless, if experts stubbornly refusing to verify (or incapable of verifying) such logical facts objectively. Each such fact may be a little brain teaser (e.g. like verifying a fact such as “3456*6543 = 22,612,608” without using a calculator) and needs to apply mind. It is certainly not hard for any researcher having a doctorate or brain😊 to verify.
What else anyone can do to compel scientists and researchers (who are working at taxpayer funded organizations that are being funded by taxpayers for finding, promoting and/or supporting scientific and technological progress) to investigate evidence for such simple logical facts, in addition to offering to face criminal prosecution, if one is wrong? (e.g. http://real-software-components.com/raju/BriefObjectiveExecicutiveSummary.pdf)
I am disparate that even open to offering bribes ☹, if bribes work 😊 (and if the bribes can be structured to pay legally as gifts or shares of new company for services). I am sure, campaign contributions (in many cases) are thinly veiled bribes. I am sure, court case could work better, but court case would take more time and money than a bribe.
Best Regards,
Raju Chiluvuri
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3. Katz-Fodorian (1963) system of binary componential analysis ignores the prototypical cognition of meaning by the human being. As some cognitive scientist observed that the meaning as endorsed by human beings, could not be analyzed by the stipulated components as humans understand meaning through prototypical cognition. What should we follow in semantic analysis:technical intelligentsia’s critical discursive habit of paraphrasing or commonsense deployment of prototypes?
4. Let us switch over to another schooling and try to understand semantic problems raised by continental philosophers (under the umbrella o fso-called Post-Formalism/ Structuralism). These Post-Formalists are talking about plural meanings of non-disposable texts as well as something called‘surplus meanings’, which is not at all analyzable or quantifiable .According to them, the meaning-site is too slippery area and any futile endeavor to formalize such site will be ended in vain. Do you think that they are neglecting ‘science’ and its formalism by promoting“un-scientific” non-formalism?

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