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4 questions
2
votes
2
answers
181
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Background for Kierstead terms
I was looking at some slides of John Longley's here, where he mentions "the Kierstead functional"
$$\lambda f.f(\lambda x.f(\lambda y.x)) \ ,$$
(where $f$ should be of type $2$, and $x,y$ of ground ...
16
votes
2
answers
3k
views
Why is there no product type in simply typed lambda-calculus?
$\DeclareMathOperator\Pair{Pair}\DeclareMathOperator\First{First}\DeclareMathOperator\Second{Second}\DeclareMathOperator\Left{Left}\DeclareMathOperator\Right{Right}\DeclareMathOperator\Choice{Choice}$...
3
votes
1
answer
404
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Is there an easy decision algorithm for the inhabitation problem for simple types?
Consider the basic system of simple types usually known as $TA_\lambda$. One can prove that (as a consequence of the Subject Reduction Property and the fact that any typable term is strongly $\beta$-...
1
vote
1
answer
169
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Interaction-based approximation for HP-complete λ-theory?
We are looking for a proof or counter-examples for the following hypothesis.
Two combinators $M$ and $N$ are solvable and equivalent in the HP-complete sensible $\lambda$-theory iff either
$$
\exists ...