3,266 research outputs found
Isomorphisms in co-TT graphs
No full text2019 Spring.Includes bibliographical references.A threshold tolerance graph is a graph where each vertex v is assigned a weight wv and a tolerance tv, and there is an edge between two vertices vx and vy if and only if wx + wy ≥ min(tx,ty). A co-TT graph is the complement of a threshold tolerance graph. Recognition of these graphs can be done in O(n2) time; however no polynomial-time algorithm to identify isomorphisms between pairs of TT or co-TT graphs was previously known. We give an algorithm to identify these isomorphisms, which takes O(n2) time
tt*-geometry and pluriharmonic maps
No full textInternational audienceIn this paper we use the real differential geometric definition of a metric (an unimodular oriented metric) tt*-bundle of Cortés and the author to define a map from the space of metric (unimodular oriented metric) tt*-bundles of rank r over a complex manifold M to the space of pluriharmonic maps from M to (respectively ), where (p,q) is the signature of the metric. In the sequel the image of the map is characterized. It follows, that in signature (r,0) the image of is the whole space of pluriharmonic maps. This generalizes a result of Dubrovin
performance of the low-rank TT-SVD for large dense tensors on modern multicore CPUs
No full textThere are several factorizations of multidimensional tensors into lower-dimensional components, known as ``tensor networks."" We consider the popular ``tensor-train"" (TT) format and ask, How efficiently can we compute a low-rank approximation from a full tensor on current multicore CPUs? Compared to sparse and dense linear algebra, kernel libraries for multilinear algebra are rare and typically not as well optimized. Linear algebra libraries like BLAS and LAPACK may provide the required operations in principle but often at the cost of additional data movements for rearranging memory layouts. Furthermore, these libraries are typically optimized for the compute-bound case (e.g., square matrix operations), whereas low-rank tensor decompositions lead to memory bandwidth limited operations. We propose a ``TT singular value decomposition"" (TT-SVD) algorithm based on two building blocks: a ``Q-less tall-skinny QR"" factorization and a fused tall-skinny matrix-matrix multiplication and reshape operation. We analyze the performance of the resulting TT-SVD algorithm using the roofline performance model. In addition, we present performance results for different algorithmic variants for shared-memory as well as distributed-memory architectures. Our experiments show that commonly used TT-SVD implementations suffer severe performance penalties. We conclude that a dedicated library for tensor factorization kernels would benefit the community: Computing a low-rank approximation can be as cheap as reading the data twice from main memory. As a consequence, an implementation that achieves realistic performance will move the limit at which one has to resort to randomized methods that only process part of the data.Numerical Analysi
"_Pst-tt!", circa 1962
No full textA dark figure marked "Merchants" opens a door labeled "Back Door Deals". Written on recto: "_Pst-tt!".Crim
Search for tt¯ H/ A→ tt¯ tt¯ production in the multilepton final state in proton–proton collisions at √s = 13 TeV with the ATLAS detector
No full textA search for a new heavy scalar or pseudo-scalar Higgs boson (H/A) produced in association with a pair of top quarks, with the Higgs boson decaying into a pair of top quarks (H/A → tt¯) is reported. The search targets a final state with exactly two leptons with same-sign electric charges or at least three leptons. The analysed dataset corresponds to an integrated luminosity of 139 fb −1 of proton–proton collisions collected at a centre-of-mass energy of 13 TeV with the ATLAS detector at the LHC. Two multivariate classifiers are used to separate the signal from the background. No significant excess of events over the Standard Model expectation is observed. The results are interpreted in the context of a type-II two-Higgs-doublet model. The observed (expected) upper limits at 95% confidence level on the tt¯ H/ A production cross-section times the branching ratio of H/A → tt¯ range between 14 (10) fb and 6 (5) fb for a heavy Higgs boson with mass between 400 GeV and 1000 GeV, respectively. Assuming that only one particle, either the scalar H or the pseudo-scalar A, contributes to the tt¯ tt¯ final state, values of tan β below 1.2 or 0.5 are excluded for a mass of 400 GeV or 1000 GeV, respectively. These exclusion ranges increase to tan β below 1.6 or 0.6 when both particles are considered. [Figure not available: see fulltext.] © 2023, The Author(s)
Search for tt ̄H/A→tt ̄tt ̄ production in proton–proton collisions at s=13 TeV with the ATLAS detector
No full textA search is presented for a heavy scalar (H) or pseudo-scalar (A) predicted by the two-Higgs-doublet models, where the H/A is produced in association with a top-quark pair (tt ̄H/A), and with the H/A decaying into a tt ̄ pair. The full LHC Run 2 proton–proton collision data collected by the ATLAS experiment is used, corresponding to an integrated luminosity of 139fb-1. Events are selected requiring exactly one or two opposite-charge electrons or muons. Data-driven corrections are applied to improve the modelling of the tt ̄+jets background in the regime with high jet and b-jet multiplicities. These include a novel multi-dimensional kinematic reweighting based on a neural network trained using data and simulations. An H/A-mass parameterised graph neural network is trained to optimise the signal-to-background discrimination. In combination with the previous search performed by the ATLAS Collaboration in the multilepton final state, the observed upper limits on the tt ̄H/A→tt ̄tt ̄ production cross-section at 95% confidence level range between 14 fb and 5.0 fb for an H/A with mass between 400 GeV and 1000 GeV, respectively. Assuming that both the H and A contribute to the tt ̄tt ̄ cross-section, tanβ values below 1.7 or 0.7 are excluded for a mass of 400 GeV or 1000 GeV, respectively. The results are also used to constrain a model predicting the pair production of a colour-octet scalar, with the scalar decaying into a tt ̄ pair
Faster tensor train decomposition for sparse data
No full textIn recent years, the application of tensors has become more widespread in fields that involve data analytics and numerical computation. Due to the explosive growth of data, low-rank tensor decompositions have become a powerful tool to harness the notorious curse of dimensionality. The main forms of tensor decomposition include CP decomposition, Tucker decomposition, tensor train (TT) decomposition, etc. Each of the existing TT decomposition algorithms, including the TT-SVD and randomized TT-SVD, is successful in the field, but neither can both accurately and efficiently decompose large-scale sparse tensors. Based on previous research, this paper proposes a new quasi-optimal fast TT decomposition algorithm for large-scale sparse tensors with proven correctness and the upper bound of computational complexity derived. It can also efficiently produce sparse TT with no numerical error and slightly larger TT-ranks on demand. In numerical experiments, we verify that the proposed algorithm can decompose sparse tensors in a much faster speed than the TT-SVD, and have advantages on speed, precision and versatility over the randomized TT-SVD and TT-cross. And, with it we can realize large-scale sparse matrix TT decomposition that was previously unachievable, enabling the tensor decomposition based algorithms to be applied in more scenarios.Green Open Access added to TU Delft Institutional Repository 'You share, we take care!' - Taverne project https://www.openaccess.nl/en/you-share-we-take-care Otherwise as indicated in the copyright section: the publisher is the copyright holder of this work and the author uses the Dutch legislation to make this work public.Team Kim Batselie
Tomb TT 62
No full textPersons and Names of the Middle Kingdom and early New Kingdom. Supplementary material to the database. Study photographs of inscriptions in Theban Tomb TT 62
The database “Persons and Names of the Middle Kingdom and early New Kingdom” (PNM) is developed as part of the projects “Umformung und Variabilität im Korpus altägyptischer Personennamen 2055–1550 v. Chr.” and “Altägyptische Titel in amtlichen und familiären Kontexten, 2055-1352 v. Chr.” at the Johannes Gutenberg University Mainz. The database includes data on Egyptian Middle Kingdom and early New Kingdom personal names, people, written sources, titles, and dossiers of persons attested in various sources. The online version of the database is currently accessible under https://pnm.uni-mainz.de/info and the dataset is made available under https://doi.org/10.5281/zenodo.1411391
Supplementary material collected during work on the database is made available online as an open digital archive associated with the database. It should not be considered as a publication of the respective archaeological structures and objects or their inscriptions. The photographs have been taken solely for the purpose of reading the inscriptions and are of a non-professional quality. The author would be happy if they could be of any help to colleagues preparing the publications of the respective archaeological structures and objects, and they are free to make any use of these open data (see below).
The first batch of supplementary material for the database contains study photographs of inscriptions in ten 18th Dynasty Theban tombs, taken during a photographic survey conducted by Alexander Ilin-Tomich from 29 November to 4 December 2023. The following tombs were visited: TT 22, 62, 140, 164, 182, 204, 228, 231, 234, 239.
This repository contains photographic documentation of tomb TT 62
Tomb TT 231
No full textPersons and Names of the Middle Kingdom and early New Kingdom. Supplementary material to the database. Study photographs of inscriptions in Theban Tomb TT 231
The database “Persons and Names of the Middle Kingdom and early New Kingdom” (PNM) is developed as part of the projects “Umformung und Variabilität im Korpus altägyptischer Personennamen 2055–1550 v. Chr.” and “Altägyptische Titel in amtlichen und familiären Kontexten, 2055-1352 v. Chr.” at the Johannes Gutenberg University Mainz. The database includes data on Egyptian Middle Kingdom and early New Kingdom personal names, people, written sources, titles, and dossiers of persons attested in various sources. The online version of the database is currently accessible under https://pnm.uni-mainz.de/info and the dataset is made available under https://doi.org/10.5281/zenodo.1411391
Supplementary material collected during work on the database is made available online as an open digital archive associated with the database. It should not be considered as a publication of the respective archaeological structures and objects or their inscriptions. The photographs have been taken solely for the purpose of reading the inscriptions and are of a non-professional quality. The author would be happy if they could be of any help to colleagues preparing the publications of the respective archaeological structures and objects, and they are free to make any use of these open data (see below).
The first batch of supplementary material for the database contains study photographs of inscriptions in ten 18th Dynasty Theban tombs, taken during a photographic survey conducted by Alexander Ilin-Tomich from 29 November to 4 December 2023. The following tombs were visited: TT 22, 62, 140, 164, 182, 204, 228, 231, 234, 239.
This repository contains photographic documentation of tomb TT 231
Tomb TT 22
No full textPersons and Names of the Middle Kingdom and early New Kingdom. Supplementary material to the database. Study photographs of inscriptions in Theban Tomb TT 22
The database “Persons and Names of the Middle Kingdom and early New Kingdom” (PNM) is developed as part of the projects “Umformung und Variabilität im Korpus altägyptischer Personennamen 2055–1550 v. Chr.” and “Altägyptische Titel in amtlichen und familiären Kontexten, 2055-1352 v. Chr.” at the Johannes Gutenberg University Mainz. The database includes data on Egyptian Middle Kingdom and early New Kingdom personal names, people, written sources, titles, and dossiers of persons attested in various sources. The online version of the database is currently accessible under https://pnm.uni-mainz.de/info and the dataset is made available under https://doi.org/10.5281/zenodo.1411391
Supplementary material collected during work on the database is made available online as an open digital archive associated with the database. It should not be considered as a publication of the respective archaeological structures and objects or their inscriptions. The photographs have been taken solely for the purpose of reading the inscriptions and are of a non-professional quality. The author would be happy if they could be of any help to colleagues preparing the publications of the respective archaeological structures and objects, and they are free to make any use of these open data (see below).
The first batch of supplementary material for the database contains study photographs of inscriptions in ten 18th Dynasty Theban tombs, taken during a photographic survey conducted by Alexander Ilin-Tomich from 29 November to 4 December 2023. The following tombs were visited: TT 22, 62, 140, 164, 182, 204, 228, 231, 234, 239.
This repository contains photographic documentation of tomb TT 22
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