DIMACS | Center for Discrete Mathematics and Theoretical Computer Science
Understanding the computational difficulty of the Minimum Circuit Size Problem (MCSP) dates back to the 1950s and has wide-ranging implications in theoretical computer science. Since MCSP is not known to be NP-hard and is believed not to be in P, it is seen as a promising NP-intermediate candidate. However, despite extensive study of MCSP, there is little evidence that it is not NP-hard. In a recent development, Murray and Williams show that MCSP is not NP-hard under TIME(n0.49) projections. Murray and Williams also conjecture that MCSP is not NP-hard under logtime-uniform AC0 reductions. We show that any super-constant multiplicative approximation of MCSP is not hard for NP (in fact, not hard for PARITY) under even non-uniform AC0 many-one reductions. This result is surprising (and nearly tight) because Allender and Hirahara show that there is a constant-factor approximation to MKTP, a problem closely related to MCSP, that is hard for PARITY under non-uniform NC0 many-one reductions. To much frustration, this PARITY hardness result is not known for MCSP, and we show that the natural way to extend it to MCSP is actually impossible.
The multi-robot path planning problem (MPP) on the plane has long been studied both as a topic of research interest and because of it's numerous applications in numerous fields. While many effective algorithms and heuristics exist for discrete MPP on a graph, up until there have been very few results for the continuous version on the plane. In this work we provide a complete algorithm that solves the MPP problem on the plane with a guarantee of constant factor optimality in expectation. We hope that our work may be a good first step into exploring this problem extensions of it in special cases that reflect real world applications.
Stadium Security has increased in recent years due to stadium attacks and harmful activity, being a threat to large crowds. Within this security, we examine Walk Through Metal Detectors as they are widely used and an important part of large crowd venue locations. Security in general, is examined to understand the process and activities taking place during real environment security processes through data collection and security software testing.
Schubert calculus studies Schubert structure constants for the cohomology rings of a homogeneous space X. In many cases, combinatorial rules involving jeu de taquin on posets associated to these spaces have given positive formulas for these constants. Schutzenberger first proved such a rule for X a Grassmanian. Chaput and Perrin extended this to products of Λ-minuscule classes of spaces under a Kac-Moody group. This includes all Schubert classes for X a minuscule variety. Meanwhile, Buch, Samuel, Thomas, and Yong extended the jeu de taquin theory to the K-theory of all minuscule varieties. We begin to develop the analogous K-theoretic jeu de taquin theory for Proctor's d-complete posets, which are the associated posets for Λ-minuscule Schubert varieties.