4,956 research outputs found
Large gaps between consecutive zeros of the Riemann zeta-function. II
Assuming the Riemann Hypothesis we show that there exist infinitely many
consecutive zeros of the Riemann zeta-function whose gaps are greater than 2.9
times the average spacing
Twists of automorphic L-functions at the central point
We study the nonvanishing of twists of automorphic L-functions at the centre
of the critical strip. Given a primitive character \chi modulo D satisfying
some technical conditions, we prove that the twisted L-functions L(f.\chi,s) do
not vanish at s=1/2 for a positive proportion of primitive forms of weight 2
and level q, for large prime q. We also investigate the central values of high
derivatives of L(f.\chi,s), and from that derive an upper bound for the average
analytic rank of the studied L-functions
A note on the second moment of automorphic L-functions
We obtain the formula for the twisted harmonic second moment of the
-functions associated with primitive Hecke eigenforms of weight 2. A
consequence of our mean value theorem is reminiscent of recent results of
Conrey and Young on the reciprocity formula for the twisted second moment of
Dirichlet -functions.Comment: 9 page
Gaps between zeros of the derivative of the Riemann \xi-function
Assuming the Riemann hypothesis, we investigate the distribution of gaps
between the zeros of \xi'(s). We prove that a positive proportion of gaps are
less than 0.796 times the average spacing and, in the other direction, a
positive proportion of gaps are greater than 1.18 times the average spacing. We
also exhibit the existence of infinitely many normalized gaps smaller (larger)
than 0.7203 (1.5, respectively).Comment: 15 page
Robust Dialog State Tracking for Large Ontologies
The Dialog State Tracking Challenge 4 (DSTC 4) differentiates itself from the
previous three editions as follows: the number of slot-value pairs present in
the ontology is much larger, no spoken language understanding output is given,
and utterances are labeled at the subdialog level. This paper describes a novel
dialog state tracking method designed to work robustly under these conditions,
using elaborate string matching, coreference resolution tailored for dialogs
and a few other improvements. The method can correctly identify many values
that are not explicitly present in the utterance. On the final evaluation, our
method came in first among 7 competing teams and 24 entries. The F1-score
achieved by our method was 9 and 7 percentage points higher than that of the
runner-up for the utterance-level evaluation and for the subdialog-level
evaluation, respectively.Comment: Paper accepted at IWSDS 201
Policy Recognition in the Abstract Hidden Markov Model
In this paper, we present a method for recognising an agent's behaviour in
dynamic, noisy, uncertain domains, and across multiple levels of abstraction.
We term this problem on-line plan recognition under uncertainty and view it
generally as probabilistic inference on the stochastic process representing the
execution of the agent's plan. Our contributions in this paper are twofold. In
terms of probabilistic inference, we introduce the Abstract Hidden Markov Model
(AHMM), a novel type of stochastic processes, provide its dynamic Bayesian
network (DBN) structure and analyse the properties of this network. We then
describe an application of the Rao-Blackwellised Particle Filter to the AHMM
which allows us to construct an efficient, hybrid inference method for this
model. In terms of plan recognition, we propose a novel plan recognition
framework based on the AHMM as the plan execution model. The Rao-Blackwellised
hybrid inference for AHMM can take advantage of the independence properties
inherent in a model of plan execution, leading to an algorithm for online
probabilistic plan recognition that scales well with the number of levels in
the plan hierarchy. This illustrates that while stochastic models for plan
execution can be complex, they exhibit special structures which, if exploited,
can lead to efficient plan recognition algorithms. We demonstrate the
usefulness of the AHMM framework via a behaviour recognition system in a
complex spatial environment using distributed video surveillance data
Gaps between zeros of the Riemann zeta-function
We prove that there exist infinitely many consecutive zeros of the Riemann
zeta-function on the critical line whose gaps are greater than times the
average spacing. Using a modification of our method, we also show that there
are even larger gaps between the multiple zeros of the zeta function on the
critical line (if such zeros exist)
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