261,290 research outputs found
Synthesizing Programs with Continuous Optimization
Automatic software generation based on some specification is known as program
synthesis. Most existing approaches formulate program synthesis as a search
problem with discrete parameters. In this paper, we present a novel formulation
of program synthesis as a continuous optimization problem and use a
state-of-the-art evolutionary approach, known as Covariance Matrix Adaptation
Evolution Strategy to solve the problem. We then propose a mapping scheme to
convert the continuous formulation into actual programs. We compare our system,
called GENESYS, with several recent program synthesis techniques (in both
discrete and continuous domains) and show that GENESYS synthesizes more
programs within a fixed time budget than those existing schemes. For example,
for programs of length 10, GENESYS synthesizes 28% more programs than those
existing schemes within the same time budget
Parametric Representation of Rank d Tensorial Group Field Theory: Abelian Models with Kinetic Term
We consider the parametric representation of the amplitudes of Abelian models
in the so-called framework of rank Tensorial Group Field Theory. These
models are called Abelian because their fields live on . We concentrate
on the case when these models are endowed with particular kinetic terms
involving a linear power in momenta. New dimensional regularization and
renormalization schemes are introduced for particular models in this class: a
rank 3 tensor model, an infinite tower of matrix models over
, and a matrix model over . For all divergent amplitudes, we
identify a domain of meromorphicity in a strip determined by the real part of
the group dimension . From this point, the ordinary subtraction program is
applied and leads to convergent and analytic renormalized integrals.
Furthermore, we identify and study in depth the Symanzik polynomials provided
by the parametric amplitudes of generic rank Abelian models. We find that
these polynomials do not satisfy the ordinary Tutte's rules
(contraction/deletion). By scrutinizing the "face"-structure of these
polynomials, we find a generalized polynomial which turns out to be stable only
under contraction.Comment: 69 pages, 35 figure
SATURN – A User’s Manual. AMDAHL V7 Version.
SATURN is a detailed traffic simulation and assignment model intended for use in the evaluation of traffic management schemes. This document describes the preparation of the required input data and gives information on how to run the model on the Leeds University Amdhal V7 computer. Also included here are details on how to update a trip matrix from traffic counts using the ME2 program in conjunction with SATURN. Other facilities available for use with the mode1,such as network plotting and matrix manipulation,are also described
Kramers-restricted self-consistent 2-spinor fields for heavy-element chemistry
The relativistic pseudopotential (PP) method is one of the most common and successful approximations in computational quantum chemistry. If suitably parameterized -- e.g., fitted to atomic valence total energies from highly accurate relativistic reference calculations --, atomic PPs provide effective (spin�orbit) 1-electron operators mimicking the chemically inert atomic core subsystem, which thus is excluded from explicit considerations. This work deals with the development of a Kramers-restricted, 2-component PP Hartree�Fock SCF program based on the spin-restricted, 1-component HF SCF modules of the "Quantum Objects Library" of C++ program modules at the Dolg and Hanrath groups at Cologne University. Kramers' restriction, i.e. time reversal symmetry, is addressed at the lowest hierarchical level of the (formally complexified) matrix algebra modules. PP matrix elements are computed using PP integral subroutines of the ARGOS program, which are interfaced to the existing structure. On this basis, a set of spin-restricted, 1-component (all-electron and) spin-free PP, and Kramers-restricted, 2-component spin--orbit PP HF SCF programs is implemented. "Optimal damping" and initial guess density matrices constructed from atomic densities are shown to improve SCF convergence significantly. As first steps towards correlated 2-component calculation schemes, a modular structure for matrix--matrix multiplication-driven 4-index integral transformations to the Fockian eigenbasis is developed, and preliminary 2-component MP2 calculations are presented
Top Pair Production Beyond Double-Pole Approximation: pp, pp~ --> 6 Fermions and 0, 1 or 2 Additional Partons
Hadron collider cross sections for tt~ production and di-lepton,
single-lepton and all-jet decays with up to 2 additional jets are calculated
using complete LO matrix elements with 6-, 7- and 8-particle final states. The
fixed-width, complex-mass and overall-factor schemes (FWS, CMS & OFS) are
employed and the quality of narrow-width and double-pole approximations (NWA &
DPA) is investigated for inclusive production and suppressed backgrounds to new
particle searches. NWA and DPA cross sections differ by 1% or less. The
inclusion of sub- and non-resonant amplitudes effects a cross section increase
of 5-8% at pp supercolliders, but only minor changes at the Tevatron. On-shell
tt~/Wtb backgrounds for the H --> WW decay in weak boson fusion, the hadronic
\tau decay of a heavy H^\pm and the \phi --> hh --> \tau\tau bb~ radion decay
at the LHC are updated, with corrections ranging from 3% to 30%. FWS and CMS
cross sections are uniformly consistent, but OFS cross sections are up to 6%
smaller for some backgrounds.Comment: 20 pages, 6 tables, 1 figur
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