Abstract. Higman’s lemma has a very elegant, non-constructive proof due to Nash-Williams [NW63] using the so-called minimal-bad-sequence argument. The objective of the present paper is to give a proof that uses the same combinatorial idea, but is constructive. For a two letter alpha-bet this was done by Coquand and Fridlender [CF94]. Here we present a proof in a theory of inductive definitions that works for arbitrary de-cidable well quasiorders.
We develop a new analysis for the length of controlled bad sequences in well-quasi-orderings based o...
Dickson’s lemma says that for every f: N → Nn there are indices k < l such that f(k) ≤ f(l), com...
AbstractAn infinite binary sequence x is defined to be(i)strongly useful if there is a computable ti...
Abstract. Higman’s lemma has a very elegant, non-constructive proof due to Nash-Williams [NW63] usin...
Abstract. Higman’s lemma has a very elegant, non-constructive proof due to Nash-Williams [NW63] usin...
We use Gödel's Dialectica interpretation to analyse Nash-Williams' elegant but non-constructive "min...
We use Gödel’s Dialectica interpretation to analyse Nash-Williams ’ elegant but non-constructive ‘m...
We present a locale that abstracts over the necessary ingredients for constructing a minimal bad seq...
This paper gives an example of such an inductive proof for a combinatorial problem. While there exis...
Abstract. This paper gives the first formalization of Kruskal’s tree the-orem in a proof assistant. ...
Kruskal’s theorem on trees is a classical result of combinatorics with important applications in com...
Kruskal’s theorem on trees is a classical result of combinatorics with important applications in com...
Higman's Lemma is a special case of the more general Kruskal's tree embedding theorem and the graph...
Kruskal's theorem on trees is a classical result of combinatorics with important applications in com...
Kruskal's theorem on trees is a classical result of combinatorics with important applications in com...
We develop a new analysis for the length of controlled bad sequences in well-quasi-orderings based o...
Dickson’s lemma says that for every f: N → Nn there are indices k < l such that f(k) ≤ f(l), com...
AbstractAn infinite binary sequence x is defined to be(i)strongly useful if there is a computable ti...
Abstract. Higman’s lemma has a very elegant, non-constructive proof due to Nash-Williams [NW63] usin...
Abstract. Higman’s lemma has a very elegant, non-constructive proof due to Nash-Williams [NW63] usin...
We use Gödel's Dialectica interpretation to analyse Nash-Williams' elegant but non-constructive "min...
We use Gödel’s Dialectica interpretation to analyse Nash-Williams ’ elegant but non-constructive ‘m...
We present a locale that abstracts over the necessary ingredients for constructing a minimal bad seq...
This paper gives an example of such an inductive proof for a combinatorial problem. While there exis...
Abstract. This paper gives the first formalization of Kruskal’s tree the-orem in a proof assistant. ...
Kruskal’s theorem on trees is a classical result of combinatorics with important applications in com...
Kruskal’s theorem on trees is a classical result of combinatorics with important applications in com...
Higman's Lemma is a special case of the more general Kruskal's tree embedding theorem and the graph...
Kruskal's theorem on trees is a classical result of combinatorics with important applications in com...
Kruskal's theorem on trees is a classical result of combinatorics with important applications in com...
We develop a new analysis for the length of controlled bad sequences in well-quasi-orderings based o...
Dickson’s lemma says that for every f: N → Nn there are indices k < l such that f(k) ≤ f(l), com...
AbstractAn infinite binary sequence x is defined to be(i)strongly useful if there is a computable ti...
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