37,264 research outputs found
Missing Elements and Missing Premises: A Combinatorial Argument for the Ontological Reduction of Chemistry
Does chemistry reduce to physics? If this means Can we derive the laws of chemistry from the laws of physics?', recent discussions suggest that the answer is no'. But sup posing that kind of reduction-- epistemological reduction'--to be impossible, the thesis of ontological reduction may still be true: that chemical properties are determined by more fundamental properties. However, even this thesis is threatened by some objections to the physicalist programme in the philosophy of mind, objections that generalize to the chemical case. Two objections are discussed: that physicalism is vacuous, and that nothing grounds the asymmetry of dependence which reductionism requires. Although it might seem rather surprising that the philosophy of chemistry is affected by shock waves from debates in the philosophy of mind, these objections show that there is an argumentative gap between, on the one hand, the theoretical connection linking chemical properties with properties at the sub-atomic level, and, on the other, the philosophical thesis of ontological reduction. The aim of this paper is to identify the missing premises (among them a theory of physical possibility) that would bridge this gap. Introduction: missing elements and the mystery of discreteness The refutation of physicalism A combinatorial theory of physical possibilia Combinatorialism and the Bohr model Objections The missing premises and a disanalogy with min
The DG-category of secondary cohomology operations
We study track categories (i.e., groupoid-enriched categories) endowed with
additive structure similar to that of a 1-truncated DG-category, except that
composition is not assumed right linear. We show that if such a track category
is right linear up to suitably coherent correction tracks, then it is weakly
equivalent to a 1-truncated DG-category. This generalizes work of the first
author on the strictification of secondary cohomology operations. As an
application, we show that the secondary integral Steenrod algebra is
strictifiable.Comment: v3: Minor revision
Extended graphical calculus for categorified quantum sl(2)
A categorification of the Beilinson-Lusztig-MacPherson form of the quantum
sl(2) was constructed in the paper arXiv:0803.3652 by the second author. Here
we enhance the graphical calculus introduced and developed in that paper to
include two-morphisms between divided powers one-morphisms and their
compositions. We obtain explicit diagrammatical formulas for the decomposition
of products of divided powers one-morphisms as direct sums of indecomposable
one-morphisms; the latter are in a bijection with the Lusztig canonical basis
elements. These formulas have integral coefficients and imply that one of the
main results of Lauda's paper---identification of the Grothendieck ring of his
2-category with the idempotented quantum sl(2)---also holds when the 2-category
is defined over the ring of integers rather than over a field.Comment: 72 pages, LaTeX2e with xypic and pstricks macro
Healthiness from Duality
Healthiness is a good old question in program logics that dates back to
Dijkstra. It asks for an intrinsic characterization of those predicate
transformers which arise as the (backward) interpretation of a certain class of
programs. There are several results known for healthiness conditions: for
deterministic programs, nondeterministic ones, probabilistic ones, etc.
Building upon our previous works on so-called state-and-effect triangles, we
contribute a unified categorical framework for investigating healthiness
conditions. We find the framework to be centered around a dual adjunction
induced by a dualizing object, together with our notion of relative
Eilenberg-Moore algebra playing fundamental roles too. The latter notion seems
interesting in its own right in the context of monads, Lawvere theories and
enriched categories.Comment: 13 pages, Extended version with appendices of a paper accepted to
LICS 201
Trace as an alternative decategorification functor
Categorification is a process of lifting structures to a higher categorical
level. The original structure can then be recovered by means of the so-called
"decategorification" functor. Algebras are typically categorified to additive
categories with additional structure and decategorification is usually given by
the (split) Grothendieck group. In this expository article we study an
alternative decategorification functor given by the trace or the zeroth
Hochschild--Mitchell homology. We show that this form of decategorification
endows any 2-representation of the categorified quantum sl(n) with an action of
the current algebra U(sl(n)[t]) on its center.Comment: 47 pages with tikz figures. arXiv admin note: text overlap with
arXiv:1405.5920 by other author
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