TY - GEN
T1 - Lossless prioritized embeddings
AU - Elkin, Michael
AU - Neiman, Ofer
N1 - Funding Information:
?This research was supported by the ISF grant No. (724/15). ?Supported in part by ISF grant No. (1817/17) and by BSF grant No. 2015813.
Publisher Copyright:
Copyright © 2020 by SIAM
PY - 2020/1/1
Y1 - 2020/1/1
N2 - Given metric spaces (X, d) and (Y, ρ) and an ordering x1, x2, . . ., xn of (X, d), an embedding f : X → Y is said to have a prioritized distortion α(·), for a function α(·), if for any pair xj, x0 of distinct points in X, the distortion provided by f for this pair is at most α(j). If Y is a normed space, the embedding is said to have prioritized dimension β(·), if f(xj) may have at most β(j) nonzero coordinates. The notion of prioritized embedding was introduced by Filtser and the current authors in [EFN18], where a rather general methodology for constructing such embeddings was developed. Though this methodology enabled [EFN18] to come up with many prioritized embeddings, it typically incurs some loss in the distortion. In other words, in the worst-case, prioritized embeddings obtained via this methodology incur distortion which is at least a constant factor off, compared to the distortion of the classical counterparts of these embeddings. This constant loss is problematic for isometric embeddings. It is also troublesome for Matousek's embedding of general metrics into l∞, which for a parameter k = 1, 2, . . ., provides distortion 2k−1 and dimension O(k log n·n1/k). In this paper we devise two lossless prioritized embeddings. The first one is an isometric prioritized embedding of tree metrics into l∞ with dimension O(log j), matching the worst-case guarantee of O(log n) of the classical embedding of Linial et al. [LLR95]. The second one is a prioritized Matousek's embedding of general metrics into l∞, which for a parameter k = 1, 2, . . ., provides prioritized distortion 2dk loglognj e− 1 and dimension O(k log n · n1/k), again matching the worst-case guarantee 2k − 1 in the distortion of the classical Matousek's embedding. We also provide a dimension-prioritized variant of Matousek's embedding. Finally, we devise prioritized embeddings of general metrics into (single) ultra-metric and of general graphs into (single) spanning tree with asymptotically optimal distortion.
AB - Given metric spaces (X, d) and (Y, ρ) and an ordering x1, x2, . . ., xn of (X, d), an embedding f : X → Y is said to have a prioritized distortion α(·), for a function α(·), if for any pair xj, x0 of distinct points in X, the distortion provided by f for this pair is at most α(j). If Y is a normed space, the embedding is said to have prioritized dimension β(·), if f(xj) may have at most β(j) nonzero coordinates. The notion of prioritized embedding was introduced by Filtser and the current authors in [EFN18], where a rather general methodology for constructing such embeddings was developed. Though this methodology enabled [EFN18] to come up with many prioritized embeddings, it typically incurs some loss in the distortion. In other words, in the worst-case, prioritized embeddings obtained via this methodology incur distortion which is at least a constant factor off, compared to the distortion of the classical counterparts of these embeddings. This constant loss is problematic for isometric embeddings. It is also troublesome for Matousek's embedding of general metrics into l∞, which for a parameter k = 1, 2, . . ., provides distortion 2k−1 and dimension O(k log n·n1/k). In this paper we devise two lossless prioritized embeddings. The first one is an isometric prioritized embedding of tree metrics into l∞ with dimension O(log j), matching the worst-case guarantee of O(log n) of the classical embedding of Linial et al. [LLR95]. The second one is a prioritized Matousek's embedding of general metrics into l∞, which for a parameter k = 1, 2, . . ., provides prioritized distortion 2dk loglognj e− 1 and dimension O(k log n · n1/k), again matching the worst-case guarantee 2k − 1 in the distortion of the classical Matousek's embedding. We also provide a dimension-prioritized variant of Matousek's embedding. Finally, we devise prioritized embeddings of general metrics into (single) ultra-metric and of general graphs into (single) spanning tree with asymptotically optimal distortion.
UR - http://www.scopus.com/inward/record.url?scp=85084039185&partnerID=8YFLogxK
U2 - 10.1137/1.9781611975994.64
DO - 10.1137/1.9781611975994.64
M3 - Conference contribution
AN - SCOPUS:85084039185
T3 - Proceedings of the Annual ACM-SIAM Symposium on Discrete Algorithms
SP - 1049
EP - 1062
BT - 31st Annual ACM-SIAM Symposium on Discrete Algorithms, SODA 2020
A2 - Chawla, Shuchi
PB - Association for Computing Machinery
T2 - 31st Annual ACM-SIAM Symposium on Discrete Algorithms, SODA 2020
Y2 - 5 January 2020 through 8 January 2020
ER -