261,290 research outputs found

    Synthesizing Programs with Continuous Optimization

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    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 ∑s∣ps∣+μ\sum_{s}|p_s| + \mu

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    We consider the parametric representation of the amplitudes of Abelian models in the so-called framework of rank dd Tensorial Group Field Theory. These models are called Abelian because their fields live on U(1)DU(1)^D. 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 Ï•2n\phi^{2n} over U(1)U(1), and a matrix model over U(1)2U(1)^2. For all divergent amplitudes, we identify a domain of meromorphicity in a strip determined by the real part of the group dimension DD. 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 dd 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.

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    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

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    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

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    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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