34,451 research outputs found
The silence of self-knowledge
Gareth Evans famously affirmed an explanatory connection between answering the question whether p and knowing whether one believes that p. This is commonly interpreted in terms of the idea that judging that p constitutes an adequate basis for the belief that one believes that p. This paper formulates and defends an alternative, more modest interpretation, which develops from the suggestion that one can know that one believes that p in judging that p
Six-Dimensional Supergravity on S^3 X AdS_3 and 2d Conformal Field Theory
In this paper we study the relation between six-dimensional supergravity
compactified on S^3 X AdS_3 and certain two-dimensional conformal field
theories. We compute the Kaluza-Klein spectrum of supergravity using
representation theory; these methods are quite general and can also be applied
to other compactifications involving anti-de Sitter spaces. A detailed
comparison between the spectrum of the two-dimensional conformal field theory
and supergravity is made, and we find complete agreement. This applies even at
the level of certain non-chiral primaries, and we propose a resolution to the
puzzle of the missing states recently raised by Vafa. As a further illustration
of the method the Kaluza-Klein spectra of F-theory on M^6 X S^3 X AdS_3 and of
M-theory on M^6 X S^2 X AdS_3 are computed, with M^6 some Calabi-Yau manifold.Comment: 32 pages, LaTeX; minor corrections, reference adde
Sterile Neutrino as a Bulk Neutrino
If light sterile neutrinos are needed to understand the neutrino puzzles, as
is currently indicated, a major theoretical challenge is to understand why its
mass is so small. It is a more serious problem than understanding the small
mass of the familiar neutrinos. We discuss a new way to solve this problem by
identifying the sterile neutrino as gauge neutral fermion propagating in the
bulk of a higher dimensional theory, with bulk size of order of a millimeter.
The smallness of its mass is then a consequence of the size of the extra
dimension and does not need the introduction of new symmetries. We present a
realistic model for neutrino masses and mixings that implements this idea.Comment: 13 pages, no figures; minor typos correcte
The consumption-tightness puzzle
This paper introduces a labor force participation choice into a labor market matching model embedded in a dynamic stochastic general equilibrium set-up with production and savings. The participation choice is modelled as a tradeoff between forgoing the expected benefits of being search active and engaging in costly labor market search. The model induces a symmetry in firmsâ and workersâ search decision since both sides of the labor market vary search effort at the extensive margins. We show that this set-up is of considerable analytical convenience and that it gives rise to a linear relationship between labor market tightness and the marginal utility of consumption. We refer to the latter as the âconsumption - tightness puzzleâ because (a) it gives rise to a number of counterfactual implications, and (b) it is a robust implication of theory. Amongst the counterfactual implications are very low volatility of tightness, procyclical unemployment, and a positively sloped Beveridge curve. These implications all derive from procyclical variations in participation rates that follow from allowing for the extensive search margin
The mixing time of the fifteen puzzle
We show that there are universal positive constants c and C such that the
mixing time T_{mix} for the fifteen puzzle in an n by n torus satisfies cn^4
log n < T_{mix} < Cn^4 log^2 n.Comment: 30 pages, 9 figure
Trains, Games, and Complexity: 0/1/2-Player Motion Planning through Input/Output Gadgets
We analyze the computational complexity of motion planning through local
"input/output" gadgets with separate entrances and exits, and a subset of
allowed traversals from entrances to exits, each of which changes the state of
the gadget and thereby the allowed traversals. We study such gadgets in the 0-,
1-, and 2-player settings, in particular extending past
motion-planning-through-gadgets work to 0-player games for the first time, by
considering "branchless" connections between gadgets that route every gadget's
exit to a unique gadget's entrance. Our complexity results include containment
in L, NL, P, NP, and PSPACE; as well as hardness for NL, P, NP, and PSPACE. We
apply these results to show PSPACE-completeness for certain mechanics in
Factorio, [the Sequence], and a restricted version of Trainyard, improving
prior results. This work strengthens prior results on switching graphs and
reachability switching games.Comment: 37 pages, 36 figure
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