TY - JOUR AB - Extending a result of Milena Radnovic and Serge Tabachnikov, we establish conditionsfor two different non-symmetric norms to define the same billiard reflection law. AU - Akopyan, Arseniy AU - Karasev, Roman ID - 7791 IS - 4 JF - European Journal of Mathematics SN - 2199-675X TI - When different norms lead to same billiard trajectories? VL - 8 ER - TY - JOUR AB - We characterize critical points of 1-dimensional maps paired in persistent homology geometrically and this way get elementary proofs of theorems about the symmetry of persistence diagrams and the variation of such maps. In particular, we identify branching points and endpoints of networks as the sole source of asymmetry and relate the cycle basis in persistent homology with a version of the stable marriage problem. Our analysis provides the foundations of fast algorithms for maintaining collections of interrelated sorted lists together with their persistence diagrams. AU - Biswas, Ranita AU - Cultrera di Montesano, Sebastiano AU - Edelsbrunner, Herbert AU - Saghafian, Morteza ID - 11660 JF - LIPIcs TI - A window to the persistence of 1D maps. I: Geometric characterization of critical point pairs ER - TY - JOUR AB - The depth of a cell in an arrangement of n (non-vertical) great-spheres in Sd is the number of great-spheres that pass above the cell. We prove Euler-type relations, which imply extensions of the classic Dehn–Sommerville relations for convex polytopes to sublevel sets of the depth function, and we use the relations to extend the expressions for the number of faces of neighborly polytopes to the number of cells of levels in neighborly arrangements. AU - Biswas, Ranita AU - Cultrera di Montesano, Sebastiano AU - Edelsbrunner, Herbert AU - Saghafian, Morteza ID - 11658 JF - Leibniz International Proceedings on Mathematics TI - Depth in arrangements: Dehn–Sommerville–Euler relations with applications ER - TY - GEN AB - Given a locally finite set A⊆Rd and a coloring χ:A→{0,1,…,s}, we introduce the chromatic Delaunay mosaic of χ, which is a Delaunay mosaic in Rs+d that represents how points of different colors mingle. Our main results are bounds on the size of the chromatic Delaunay mosaic, in which we assume that d and s are constants. For example, if A is finite with n=#A, and the coloring is random, then the chromatic Delaunay mosaic has O(n⌈d/2⌉) cells in expectation. In contrast, for Delone sets and Poisson point processes in Rd, the expected number of cells within a closed ball is only a constant times the number of points in this ball. Furthermore, in R2 all colorings of a dense set of n points have chromatic Delaunay mosaics of size O(n). This encourages the use of chromatic Delaunay mosaics in applications. AU - Biswas, Ranita AU - Cultrera di Montesano, Sebastiano AU - Draganov, Ondrej AU - Edelsbrunner, Herbert AU - Saghafian, Morteza ID - 15090 T2 - arXiv TI - On the size of chromatic Delaunay mosaics ER - TY - JOUR AB - It is practical to collect a huge amount of movement data and environmental context information along with the health signals of individuals because there is the emergence of new generations of positioning and tracking technologies and rapid advancements of health sensors. The study of the relations between these datasets and their sequence similarity analysis is of interest to many applications such as health monitoring and recommender systems. However, entering all movement parameters and health signals can lead to the complexity of the problem and an increase in its computational load. In this situation, dimension reduction techniques can be used to avoid consideration of simultaneous dependent parameters in the process of similarity measurement of the trajectories. The present study provides a framework, named CaDRAW, to use spatial–temporal data and movement parameters along with independent context information in the process of measuring the similarity of trajectories. In this regard, the omission of dependent movement characteristic signals is conducted by using an unsupervised feature selection dimension reduction technique. To evaluate the effectiveness of the proposed framework, it was applied to a real contextualized movement and related health signal datasets of individuals. The results indicated the capability of the proposed framework in measuring the similarity and in decreasing the characteristic signals in such a way that the similarity results -before and after reduction of dependent characteristic signals- have small differences. The mean differences between the obtained results before and after reducing the dimension were 0.029 and 0.023 for the round path, respectively. AU - Goudarzi, Samira AU - Sharif, Mohammad AU - Karimipour, Farid ID - 10208 JF - Journal of Ambient Intelligence and Humanized Computing KW - general computer science SN - 1868-5137 TI - A context-aware dimension reduction framework for trajectory and health signal analyses VL - 13 ER - TY - JOUR AU - Adams, Henry AU - Kourimska, Hana AU - Heiss, Teresa AU - Percival, Sarah AU - Ziegelmeier, Lori ID - 10071 IS - 9 JF - Notices of the American Mathematical Society SN - 0002-9920 TI - How to tutorial-a-thon VL - 68 ER - TY - CONF AB - How information is created, shared and consumed has changed rapidly in recent decades, in part thanks to new social platforms and technologies on the web. With ever-larger amounts of unstructured and limited labels, organizing and reconciling information from different sources and modalities is a central challenge in machine learning. This cutting-edge tutorial aims to introduce the multimodal entailment task, which can be useful for detecting semantic alignments when a single modality alone does not suffice for a whole content understanding. Starting with a brief overview of natural language processing, computer vision, structured data and neural graph learning, we lay the foundations for the multimodal sections to follow. We then discuss recent multimodal learning literature covering visual, audio and language streams, and explore case studies focusing on tasks which require fine-grained understanding of visual and linguistic semantics question answering, veracity and hatred classification. Finally, we introduce a new dataset for recognizing multimodal entailment, exploring it in a hands-on collaborative section. Overall, this tutorial gives an overview of multimodal learning, introduces a multimodal entailment dataset, and encourages future research in the topic. AU - Ilharco, Cesar AU - Shirazi, Afsaneh AU - Gopalan, Arjun AU - Nagrani, Arsha AU - Bratanič, Blaž AU - Bregler, Chris AU - Liu, Christina AU - Ferreira, Felipe AU - Barcik, Gabriek AU - Ilharco, Gabriel AU - Osang, Georg F AU - Bulian, Jannis AU - Frank, Jared AU - Smaira, Lucas AU - Cao, Qin AU - Marino, Ricardo AU - Patel, Roma AU - Leung, Thomas AU - Imbrasaite, Vaiva ID - 10367 SN - 9-781-9540-8557-2 T2 - 59th Annual Meeting of the Association for Computational Linguistics and the 11th International Joint Conference on Natural Language Processing, Tutorial Abstracts TI - Recognizing multimodal entailment ER - TY - JOUR AB - We consider infinite-dimensional properties in coarse geometry for hyperspaces consisting of finite subsets of metric spaces with the Hausdorff metric. We see that several infinite-dimensional properties are preserved by taking the hyperspace of subsets with at most n points. On the other hand, we prove that, if a metric space contains a sequence of long intervals coarsely, then its hyperspace of finite subsets is not coarsely embeddable into any uniformly convex Banach space. As a corollary, the hyperspace of finite subsets of the real line is not coarsely embeddable into any uniformly convex Banach space. It is also shown that every (not necessarily bounded geometry) metric space with straight finite decomposition complexity has metric sparsification property. AU - Weighill, Thomas AU - Yamauchi, Takamitsu AU - Zava, Nicolò ID - 10608 JF - European Journal of Mathematics SN - 2199-675X TI - Coarse infinite-dimensionality of hyperspaces of finite subsets ER - TY - CONF AB - matching is compatible to two or more labeled point sets of size n with labels {1,…,n} if its straight-line drawing on each of these point sets is crossing-free. We study the maximum number of edges in a matching compatible to two or more labeled point sets in general position in the plane. We show that for any two labeled convex sets of n points there exists a compatible matching with ⌊2n−−√⌋ edges. More generally, for any ℓ labeled point sets we construct compatible matchings of size Ω(n1/ℓ) . As a corresponding upper bound, we use probabilistic arguments to show that for any ℓ given sets of n points there exists a labeling of each set such that the largest compatible matching has O(n2/(ℓ+1)) edges. Finally, we show that Θ(logn) copies of any set of n points are necessary and sufficient for the existence of a labeling such that any compatible matching consists only of a single edge. AU - Aichholzer, Oswin AU - Arroyo Guevara, Alan M AU - Masárová, Zuzana AU - Parada, Irene AU - Perz, Daniel AU - Pilz, Alexander AU - Tkadlec, Josef AU - Vogtenhuber, Birgit ID - 9296 SN - 03029743 T2 - 15th International Conference on Algorithms and Computation TI - On compatible matchings VL - 12635 ER - TY - JOUR AB - Given a locally finite set 𝑋⊆ℝ𝑑 and an integer 𝑘≥0, we consider the function 𝐰𝑘:Del𝑘(𝑋)→ℝ on the dual of the order-k Voronoi tessellation, whose sublevel sets generalize the notion of alpha shapes from order-1 to order-k (Edelsbrunner et al. in IEEE Trans Inf Theory IT-29:551–559, 1983; Krasnoshchekov and Polishchuk in Inf Process Lett 114:76–83, 2014). While this function is not necessarily generalized discrete Morse, in the sense of Forman (Adv Math 134:90–145, 1998) and Freij (Discrete Math 309:3821–3829, 2009), we prove that it satisfies similar properties so that its increments can be meaningfully classified into critical and non-critical steps. This result extends to the case of weighted points and sheds light on k-fold covers with balls in Euclidean space. AU - Edelsbrunner, Herbert AU - Nikitenko, Anton AU - Osang, Georg F ID - 9465 IS - 1 JF - Journal of Geometry SN - 00472468 TI - A step in the Delaunay mosaic of order k VL - 112 ER -