Abstract: We define a new topological summary for data that we call the persistence landscape. Since this summary lies in a vector space, it is easy to combine with tools from statistics and machine learning, in contrast to the standard topological summaries. Viewed as a random variable with values in a Banach space, this summary obeys a strong law of large numbers and a central limit theorem. We show how a number of standard statistical tests can be used for statistical inference using this summary. We also prove that this summary is stable and that it can be used to provide lower bounds for the bottleneck and Wasserstein distances.

Abstract: This article contains a proof of the MDS conjecture for k ? 2p ? 2. That is, that if S is a set of vectors of $${{\mathbb F}_q^k}$$ in which every subset of S of size k is a basis, where q = p h , p is prime and q is not and k ? 2p ? 2, then |S| ? q + 1. It also contains a short proof of the same fact for k ? p, for all q.

Abstract: We show that Kahan's discretization of quadratic vector fields is equivalent to a Runge--Kutta method. When the vector field is Hamiltonian on either a symplectic vector space or a Poisson vector space with constant Poisson structure, the map determined by this discretization has a conserved modified Hamiltonian and an invariant measure, a combination previously unknown amongst Runge--Kutta methods applied to nonlinear vector fields. This produces large classes of integrable rational mappings in two and three dimensions, explaining some of the integrable cases that were previously known.

Abstract: A manifold is multisymplectic, or more specifically n-plectic, if it is equipped with a closed nondegenerate differential form of degree n + 1. In previous work with Baez and Hoffnung, we described how the ‘higher analogs’ of the algebraic and geometric structures found in symplectic geometry should naturally arise in 2-plectic geometry. In particular, just as a symplectic manifold gives a Poisson algebra of functions, any 2-plectic manifold gives a Lie 2-algebra of 1-forms and functions. Lie n-algebras are examples of L ∞-algebras: graded vector spaces equipped with a collection of skew-symmetric multi-brackets that satisfy a generalized Jacobi identity. Here, we generalize our previous result. Given an n-plectic manifold, we explicitly construct a corresponding Lie n-algebra on a complex consisting of differential forms whose multi-brackets are specified by the n-plectic structure. We also show that any n-plectic manifold gives rise to another kind of algebraic structure known as a differential graded Leibniz algebra. We conclude by describing the similarities between these two structures within the context of an open problem in the theory of strongly homotopy algebras. We also mention a possible connection with the work of Barnich, Fulp, Lada, and Stasheff on the Gelfand–Dickey–Dorfman formalism.

Abstract: Metrics on shape space are used to describe deformations that take one shape to another, and to determine a distance between them. We study a family of metrics on the space of curves, that includes several recently proposed metrics, for which the metrics are characterised by mappings into vector spaces where geodesics can be easily computed. This family consists of Sobolev-type Riemannian metrics of order one on the space $\text{Imm}(S^1,\mathbb R^2)$ of parametrized plane curves and the quotient space $\text{Imm}(S^1,\mathbb R^2)/\text{Diff}(S^1)$ of unparametrized curves. For the space of open parametrized curves we find an explicit formula for the geodesic distance and show that the sectional curvatures vanish on the space of parametrized and are non-negative on the space of unparametrized open curves. For the metric, which is induced by the "R-transform", we provide a numerical algorithm that computes geodesics between unparameterised, closed curves, making use of a constrained formulation that is implemented numerically using the RATTLE algorithm. We illustrate the algorithm with some numerical tests that demonstrate it's efficiency and robustness.

Abstract: In this paper we propose a framework for modeling the intrinsic dimensionality of data sets. The models can be viewed as generalizations of the expansion dimension, which was originally proposed for the analysis of certain similarity search indices using the Euclidean distance metric. Here, we extend the original model to other metric spaces: vector spaces with the $L_p$ or vector angle (cosine similarity) distance measures, as well as product spaces for categorical data. We also provide a practical guide for estimating both local and global intrinsic dimensionality. The estimates of data complexity can subsequently be used in the design and analysis of algorithms for data mining applications such as search, clustering, classification, and outlier detection.

Abstract: In this work we explore error-correcting codes derived from the "lifting" of "affine-invariant" codes. Affine-invariant codes are simply linear codes whose coordinates are a vector space over a field and which are invariant under affine-transformations of the coordinate space. Lifting takes codes defined over a vector space of small dimension and lifts them to higher dimensions by requiring their restriction to every subspace of the original dimension to be a codeword of the code being lifted. While the operation is of interest on its own, this work focusses on new ranges of parameters that can be obtained by such codes, in the context of local correction and testing. In particular we present four interesting ranges of parameters that can be achieved by such lifts, all of which are new in the context of affine-invariance and some may be new even in general. The main highlight is a construction of high-rate codes with sublinear time decoding. The only prior construction of such codes is due to Kopparty, Saraf and Yekhanin [33]. All our codes are extremely simple, being just lifts of various parity check codes (codes with one symbol of redundancy), and in the final case, the lift of a Reed-Solomon code.We also present a simple connection between certain lifted codes and lower bounds on the size of "Nikodym sets". Roughly, a Nikodym set in Fqm is a set S with the property that every point has a line passing through it which is almost entirely contained in S. While previous lower bounds on Nikodym sets were roughly growing as qm/2m, we use our lifted codes to prove a lower bound of (1 - o(1))qm for fields of constant characteristic.

Abstract: In [M. Kontsevich and Y. Soibelman, Cohomological Hall algebra, exponential Hodge structures and motivic Donaldson–Thomas invariants, Preprint (2011), arXiv:1006.2706v2[math.AG]], the authors, in particular, associate to each finite quiver Q with a set of vertices I the so-called cohomological Hall algebra ℋ, which is ℤI≥0-graded. Its graded component ℋγ is defined as cohomology of the Artin moduli stack of representations with dimension vector γ. The product comes from natural correspondences which parameterize extensions of representations. In the case of a symmetric quiver, one can refine the grading to ℤI≥0×ℤ, and modify the product by a sign to get a super-commutative algebra (ℋ,⋆) (with parity induced by the ℤ-grading). It is conjectured in [M. Kontsevich and Y. Soibelman, Cohomological Hall algebra, exponential Hodge structures and motivic Donaldson–Thomas invariants, Preprint (2011), arXiv:1006.2706v2[math.AG]] that in this case the algebra (ℋ⊗ℚ,⋆) is free super-commutative generated by a ℤI≥0×ℤ-graded vector space of the form V =Vprim ⊗ℚ[x] , where x is a variable of bidegree (0,2)∈ℤI≥0×ℤ, and all the spaces ⨁ k∈ℤVprimγ,k, γ∈ℤI≥0. are finite-dimensional. In this paper we prove this conjecture (Theorem 1.1). We also prove some explicit bounds on pairs (γ,k) for which Vprimγ,k≠0 (Theorem 1.2). Passing to generating functions, we obtain the positivity result for quantum Donaldson–Thomas invariants, which was used by Mozgovoy to prove Kac’s conjecture for quivers with sufficiently many loops [S. Mozgovoy, Motivic Donaldson–Thomas invariants and Kac conjecture, Preprint (2011), arXiv:1103.2100v2[math.AG]]. Finally, we mention a connection with the paper of Reineke [M. Reineke, Degenerate cohomological Hall algebra and quantized Donaldson–Thomas invariants for m-loop quivers, Preprint (2011), arXiv:1102.3978v1[math.RT]].

Abstract: 1 Modular Number Systems.- 2 Complex and Hyperbolic Numbers.- 3 Geometric Algebra.- 4 Vector Spaces and Matrices.- 5 Outer Product and Determinants.- 6 Systems of Linear Equations.- 7 Linear Transformations on R^n.- 8 Structure of a Linear Operator.- 9 Linear and Bilinear Forms.- 10 Hermitian Inner Product Spaces.- 11 Geometry of Moving Planes.- 12 Representations of the Symmetric Group.- 13 Calculus on m-Surfaces.- 14 Differential Geometry of Curves.- 15 Differential Geometry of k-Surfaces.- 16 Mappings Between Surfaces.- 17 Non-Euclidean and Projective Geometries.- 18 Lie Groups and Lie Algebras.- References.- Symbols.

Abstract: Information retrieval is great technology behind web search services. In information retrieval, it is common to model index terms and documents as vectors in a suitably defined vector space. The vector space model is one of the classical and widely applied retrieval models to evaluate relevance of web page. The retrieval operation consists of computing the cosine similarity function between a given query vector and the set of documents vector and then ranking documents accordingly. In this paper, we present different approaches of vector space model to compute similarity score of hits from search engine and more importantly, it is felt that this investigation will lead to a clearer understanding of the issues and problems in using the vector space model in information retrieval and our work intends to discuss the main aspects of Vector space models and provide a comprehensive comparison for TermCount model, Tf-Idf model and Vector space model based on normalization.

Abstract: An L 2 version of the Serre duality on domains in complex manifolds involving duality of Hilbert space realizations of the @-operator is established. This duality is used to study the solution of the @-equation with prescribed support. Applications are given to @-closed extension of forms, as well to Bochner-Hartogs type extension of CR functions. comp (;E � ) with the quotient topology, where we endow spaces of compactly supported forms with the natural inductive limit topology. In fact, condition that the two maps in (1) have closed range is also necessary for the duality theorem to hold (see (9); also see (26, 27, 28) for further results of this type.) Serre's original proof (33) is based on sheaf theory and the theory of topological vector spaces. A different approach to this result, in the case when is a compact complex manifold, was given by Kodaira using Hodge theory (see (23) or (7).) In this note we extend Kodaira's method to non-compact Hermitian manifolds to obtain an L 2 analog of the Serre duality. Special cases of Serre-duality using L 2 methods have appeared before in many contexts (see (25), or (11, Theorem 5.1.7) and (19, 20), for example.) Our treatment aims to streamline and systematize these results, with emphasis on non-compact manifolds, and point out its close relation with the choice of L 2 -realizations of the Cauchy-Riemann operator @, or alternatively, choice of boundary conditions for the L 2 -realizations of the formal complex Laplacian @E#E + #E@E. The L 2 -duality can be interpreted in many ways. At one level, it is a duality between the standard � - Laplacian with @-Neumann boundary conditions, and thec-Laplacian with dual ( "@-Dirichlet") boundary conditions. Using another approach, results regarding solution of the @-equation in L 2 can be converted to statements regarding the solution of the @c equation. This leads to a solution of the @-Cauchy problem, i.e., solution of the @-equation with prescribed support. At the heart of the matter lies the existence of

Abstract: In this paper, we obtain some stability results for parametric weak generalized Ky Fan Inequality with set-valued mappings. Under new assumptions, which are weaker than the assumption of C-strict monotonicity, we provide sufficient conditions for the lower semicontinuity of the solution maps to two classes of parametric weak generalized Ky Fan Inequalities in Hausdorff topological vector spaces. These results extend and improve some results in the literature.

Abstract: A "$2$-group'' is a category equipped with a multiplication satisfying laws like those of a group. Just as groups have representations on vector spaces, $2$-groups have representations on "$2$-vector spaces'', which are categories analogous to vector spaces. Unfortunately, Lie $2$-groups typically have few representations on the finite-dimensional $2$-vector spaces introduced by Kapranov and Voevodsky. For this reason, Crane, Sheppeard and Yetter introduced certain infinite-dimensional $2$-vector spaces called ``measurable categories'' (since they are closely related to measurable fields of Hilbert spaces), and used these to study infinite-dimensional representations of certain Lie $2$-groups. Here they continue this work. They begin with a detailed study of measurable categories. Then they give a geometrical description of the measurable representations, intertwiners and $2$-intertwiners for any skeletal measurable $2$-group. They study tensor products and direct sums for representations, and various concepts of subrepresentation. They describe direct sums of intertwiners, and sub-intertwiners--features not seen in ordinary group representation theory and study irreducible and indecomposable representations and intertwiners. They also study "irretractable'' representations--another feature not seen in ordinary group representation theory. Finally, they argue that measurable categories equipped with some extra structure deserve to be considered "separable $2$-Hilbert spaces'', and compare this idea to a tentative definition of $2$-Hilbert spaces as representation categories of commutative von Neumann algebras.

Abstract: 1. Linear Equations 2. Euclidean Space 3. Matrices 4. Subspaces 5. Determinants 6. Eigenvalues and Eigenvectors 7. Vector Spaces 8. Orthogonality 9. Linear Transformations 10. Inner Product Spaces 11. Additional Topics and Applications

Abstract: Let $V$ be a vector space over a field $F$, $V^*$ its dual space and $L(V)$ the algebra of all linear operators on $V$. For an operator $a\in L(V)$ let $a*$ be its adjoint acting on $V*$, and for a subset $R$ of $L(V)$ let $R"$ be its bicommutant. If $R$ is the subalgebra of $L(V)$ generated by an operator $a$, we prove that the set $Z:={b*: b\in R}"$ is contained in ${b*: b\in R"}$; moreover $Z$ is described. This inclusion is equality if $V$ as a module over the polynomial algebra $R=F[t]$ via $t\mapsto a$ is nice enough (say torsion, or injective, or if it contains a copy of $R$ as a direct summand). Further, under the same assumption about $V$ for any $b\in L(V)$, $b\in(a)"$ if and only if the derivations $d_a$ and $d_b$ satisfy $d_b(F(V))\subseteq d_a(F(V))$, where $F(V)$ is the set of all finite rank operators on $V$. The inclusion $d_b(L(V))\subseteq d_a(L(V))$ also holds under these conditions.

Abstract: Two related constructions are associated with screening operators in models of two-dimensional conformal field theory. One is a local system constructed in terms of the braided vector space X spanned by the screening species in a given CFT model and the space of vertex operators Y and the other is the Nichols algebra 𝔅(X) and the category of its Yetter–Drinfeld modules, which we propose as an algebraic counterpart, in a "braided" version of the Kazhdan–Lusztig duality, of the representation category of vertex-operator algebras realized in logarithmic CFT models.

Abstract: The Kalman variety of a linear subspace in a vector space consists of all endomorphism that possess an eigenvector in that subspace. We study the defining polynomials and basic geometric invariants of the Kalman variety.

Abstract: D. Hart, A. Iosevich, D. Koh, S. Senger and I. Uriarte-Tuero (2008) showed that the distance graphs has kaleidoscopic pseudo-random property, i.e. sufficiently large subsets of d-dimensional vector spaces over finite fields contain every possible finite configurations. In this paper we study the kaleidoscopic pseudo-randomness of finite Euclidean graphs using probabilistic methods.

Abstract: We develop an algebraic version of Cartan’s method of equivalence or an analog of Tanaka prolongation for the (extrinsic) geometry of curves of flags of a vector space W with respect to the action of a subgroup G of GL(W). Under some natural assumptions on the subgroup G and on the flags, one can pass from the filtered objects to the corresponding graded objects and describe the construction of canonical bundles of moving frames for these curves in the language of pure linear algebra. The scope of applicability of the theory includes geometry of natural classes of curves of flags with respect to reductive linear groups or their parabolic subgroups. As simplest examples, this includes the projective and affine geometry of curves. The case of classical groups is considered in more detail.

Abstract: We consider the rational vector space generated by all rational homology spheres up to orientation-preserving homeomorphism, and the filtration defined on this space by Lagrangian-preserving rational homology handlebody replacements. We identify the graded space associated with this filtration with a graded space of augmented Jacobi diagrams.

Abstract: This paper studies geometric engineering, in the simplest possible case of rank one (Abelian) gauge theory on the affine plane and the resolved conifold. We recall the identification between Nekrasov's partition function and a version of refined Donaldson-Thomas theory, and study the relationship between the underlying vector spaces. Using a purity result, we identify the vector space underlying refined Donaldson-Thomas theory on the conifold geometry as the exterior space of the space of polynomial functions on the affine plane, with the (Lefschetz) SL(2)-action on the threefold side being dual to the geometric SL(2)-action on the affine plane. We suggest that the exterior space should be a module for the (explicitly not yet known) cohomological Hall algebra (algebra of BPS states) of the conifold.

Abstract: In this paper, we consider strong form of a vector equilibrium problem and establish some existence results for solutions of such a problem in the setting of topological vector spaces. We provide several coercivity conditions under which strong vector equilibrium problem has a solution. Our results generalize and extend the results of Bianchi and Pini [10] to the topological vector space setting.

Abstract: This new textbook explains how to identify ill-posed inverse problems arising in practice and how to design computational solution methods for them; explains computational approaches in a hands-on fashion, with related codes available on a website; and serves as a convenient entry point to practical inversion. It is the only mathematical textbook with a thorough treatment of electrical impedance tomography, and these sections are suitable for beginning and experienced researchers in mathematics and engineering. 2012 • xiv + 351 pages • Softcover • 978-1-611972-33-7 List Price $84.00 • SIAM Member Price $58.80 • CS10

Abstract: In this paper, we discuss elliptic genera of (2,2) and (0,2) supersymmetric Landau-Ginzburg models over nontrivial spaces, i.e., nonlinear sigma models on nontrivial noncompact manifolds with superpotential, generalizing old computations in Landau-Ginzburg models over (orbifolds of) vector spaces. For Landau-Ginzburg models in the same universality class as nonlinear sigma models, we explicitly check that the elliptic genera of the Landau-Ginzburg models match that of the nonlinear sigma models, via a Thom class computation of a form analogous to that appearing in recent studies of other properties of Landau-Ginzburg models on nontrivial spaces.

Abstract: Preface.- 1 Analytic Geometry of Euclidean Spaces.- 2 Systems of Linear Equations, Matrices.- 3 Vector Spaces and Subspaces.- 4 Linear Transformations.- 5 Orthogonal Projections and Bases.- 6 Determinants.- 7 Eigenvalues and Eigenvectors.- 8 Numerical Methods.- 9 Appendices.