Research Statement Stephen Binns
نویسنده
چکیده
My primary research interest is in computability and complexity theory. More specifically, I have an active research program in the area of effective dimension theory and randomness. Computability theory was first developed in the 1930s and ’40s by Alan Turing who has come to be seen, along with Gödel and Tarski, as one one of the founders of modern mathematical logic. The subject developed over the 20th century and has branched into many different sub disciplines including the study of resource-bounded complexity (in which the famous P6=NP problem is formulated), randomness, and descriptive complexity. It is in these last two fields that I am currently concentrating my research energies. Descriptive complexity begins with the concept of Kolmogorov complexity. This defines the complexity of a finite mathematical object to be the length of the shortest computer program that will output the object. It is meant to capture the intuitive notion that a simple finite object is more succinctly described than a complex one. This idea is quickly extended to infinite objects (characterised as infinite binary sequences) by effective packing dimension, which is defined to be
منابع مشابه
Finding paths through narrow and wide trees
We consider two axioms of second-order arithmetic. These axioms assert, in two different ways, that infinite but narrow binary trees always have infinite paths. We show that both axioms are strictly weaker than Weak König’s Lemma, and incomparable in strength to the dual statement (WWKL) that wide binary trees have paths.
متن کاملSmall Π 01 Classes . Stephen Binns
The property of smallness for Π1 classes is introduced and is investigated with respect to Medvedev and Muchnik degree. It is shown that the property of containing a small Π1 class depends only on the Muchnik degree of a Π1 class. A comparison is made with the idea of thinness for Π1 classes
متن کاملMass problems and density
Recall that Ew is the lattice of Muchnik degrees of nonempty effectively compact sets in Euclidean space. We solve a long-standing open problem by proving that Ew is dense, i.e., satis es 8x8y (x < y ) 9z (x < z < y)). Our proof combines an oracle construction with hyperarithmetical theory.
متن کاملRelative Kolmogorov complexity and geometry
We use the connection of Hausdorff dimension and Kolmogorov complexity to describe a geometry on the Cantor set including concepts of angle, projections and scalar multiplication. A question related to compressibility is addressed using these geometrical ideas.
متن کاملEmbeddings into the Medvedev and Muchnik lattices of Π1 classes
Let Pw and PM be the countable distributive lattices of Muchnik and Medvedev degrees of non-empty Π1 subsets of 2 , under Muchnik and Medvedev reducibility, respectively. We show that all countable distributive lattices are lattice-embeddable below any non-zero element of Pw. We show that many countable distributive lattices are lattice-embeddable below any non-zero element of PM .
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