Aug 21, 2021 · Decidable means there is a Turing-machine that accepts all and only instances of that language, but also explicitly rejects when input is not that language. So, this Turing-machine will …

Aug 28, 2019 · So whether a theory T is decidable is an epistemological fact. A statement about what we can effectively know, but completeness is a metaphysical fact about the theory.

Mar 8, 2011 · What is difference between "recognizable" and "decidable" in context of Turing machines?

Dec 26, 2020 · Let's say checking if a proof is valid is decidable. Then surely we can just enumerate the proofs then check if it's valid. This seems to be a semi-decidable procedure. But why …

Oct 14, 2023 · A formal system comes with both a syntactic component, which determines the notion of provability (⊢ ⊢), and a semantic component, which determines the notion of truth (⊨ ⊨). For this …

Apr 9, 2021 · We know that a set is decidable iff the set and its complement are both semi-decidable. Thus, the undecidability of validity implies that the complement of the set of valid formulas is not semi …

Apr 13, 2021 · 0 Please check if this answer looks ok: It is decidable, but not in $|Q|+|w|+2021$ steps. Assumption: TM only moves left or right on reading any input, and doesn't stay at same place …

May 29, 2012 · It seems very confusing that real closed field (which also can be used as the theory of real number) is decidable, while Peano arithmetic, which seems to be a subset of real closed field is …

Jul 29, 2022 · How to prove that the union of two semi decidable languages ist semi decidable. Ask Question Asked 3 years, 6 months ago Modified 1 year, 9 months ago

Jan 21, 2018 · 3 Undecidable is undecidable under certain deductive system. Decidable means that it is a theorem or its negation is a theorem, understood in a very specific sense. A theorem here is the …