8 research outputs found
Church's thesis and related axioms in Coq's type theory
"Church's thesis" () as an axiom in constructive logic states
that every total function of type is computable,
i.e. definable in a model of computation. is inconsistent in both
classical mathematics and in Brouwer's intuitionism since it contradicts Weak
K\"onig's Lemma and the fan theorem, respectively. Recently, was
proved consistent for (univalent) constructive type theory.
Since neither Weak K\"onig's Lemma nor the fan theorem are a consequence of
just logical axioms or just choice-like axioms assumed in constructive logic,
it seems likely that is inconsistent only with a combination of
classical logic and choice axioms. We study consequences of and
its relation to several classes of axioms in Coq's type theory, a constructive
type theory with a universe of propositions which does neither prove classical
logical axioms nor strong choice axioms.
We thereby provide a partial answer to the question which axioms may preserve
computational intuitions inherent to type theory, and which certainly do not.
The paper can also be read as a broad survey of axioms in type theory, with all
results mechanised in the Coq proof assistant