Definition of undecidable in English:

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Pronunciation: /ʌndɪˈsʌɪdəb(ə)l/


1Not able to be firmly established or refuted: the facts of Christ’s existence are ultimately undecidable
1.1 Logic (Of a proposition or theorem) not able to be proved or disproved.
Example sentences
  • All we could achieve by our mathematics would be non-constructive existence proofs that told us that they existed, in much the same manner that we can deduce the existence of undecidable propositions.
  • Godel showed that in any formal system adequate for number theory there is an undecidable formula, that is, a formula such that neither it nor its negation can be proved.
  • In Undecidable theories Tarski showed that group theory, lattices, abstract projective geometry, closure algebras and others mathematical systems are undecidable.



Pronunciation: /ʌndɪsʌɪdəˈbɪlɪti/
Example sentences
  • Such an attempt quickly presents the problem of undecidability, an interesting principle with wide-ranging implications.
  • But, in the haze and visual undecidability of Lyons' St Albans facades, perhaps some remnants of both these lost ideals also hover.
  • Such concepts point to the undecidability of affect, its existence in the self and the other, the film and the theorist.
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