A Compactness Theorem For Affine Equivalence-Classes of Convex Regions

1951 ◽  
Vol 3 ◽  
pp. 54-61 ◽  
Author(s):  
A. M. Macbeath
Keyword(s):  
Lower Bound ◽  
Continuous Functions ◽  
Equivalence Classes ◽  
Compactness Theorem ◽  
Upper And Lower Bounds ◽  
Geometry Of Numbers ◽  
Selection Theorem ◽  
Critical Determinant ◽  
Affine Equivalence ◽  
Affine Invariants

In some parts of the Geometry of Numbers it is convenient to know that certain affine invariants associated with convex regions attain their upper and lower bounds. A classical example is the quotient of the critical determinant by the content (if the region is symmetrical) for which Minkowski determined the exact lower bound 2–n. The object of this paper is to prove that for continuous functions of bounded regions the bounds are attained. The result is, of course, deduced from the selection theorem of Blaschke, and itself is a compactness theorem about the space of affine equivalence-classes.

scholarly journals A Lower Bound for the Query Phase of Contraction Hierarchies and Hub Labels and a Provably Optimal Instance-Based Schema

Algorithms ◽  
2021 ◽  
Vol 14 (6) ◽  
pp. 164
Author(s):  
Tobias Rupp ◽  
Stefan Funke
Keyword(s):  
Lower Bound ◽  
Lower Bounds ◽  
Real World ◽  
Road Network ◽  
Upper And Lower Bounds ◽  
Bounded Degree ◽  
Shortest Path Routing ◽  
Graph Classes ◽  
Speed Up ◽  
To Come

We prove a Ω(n) lower bound on the query time for contraction hierarchies (CH) as well as hub labels, two popular speed-up techniques for shortest path routing. Our construction is based on a graph family not too far from subgraphs that occur in real-world road networks, in particular, it is planar and has a bounded degree. Additionally, we borrow ideas from our lower bound proof to come up with instance-based lower bounds for concrete road network instances of moderate size, reaching up to 96% of an upper bound given by a constructed CH. For a variant of our instance-based schema applied to some special graph classes, we can even show matching upper and lower bounds.

scholarly journals A new metric between distributions of point processes

2008 ◽  
Vol 40 (03) ◽  
pp. 651-672 ◽  
Author(s):  
Dominic Schuhmacher ◽  
Aihua Xia
Keyword(s):  
Point Processes ◽  
Relative Difference ◽  
Continuous Functions ◽  
Upper And Lower Bounds ◽  
Point Pattern ◽  
Multiple Point ◽  
Finite Point ◽  
Lipschitz Continuous Functions ◽  
Lipschitz Continuous ◽  
Comprehensive Collection

Most metrics between finite point measures currently used in the literature have the flaw that they do not treat differing total masses in an adequate manner for applications. This paper introduces a new metric d̅ 1 that combines positional differences of points under a closest match with the relative difference in total mass in a way that fixes this flaw. A comprehensive collection of theoretical results about d̅ 1 and its induced Wasserstein metric d̅ 2 for point process distributions are given, including examples of useful d̅ 1-Lipschitz continuous functions, d̅ 2 upper bounds for the Poisson process approximation, and d̅ 2 upper and lower bounds between distributions of point processes of independent and identically distributed points. Furthermore, we present a statistical test for multiple point pattern data that demonstrates the potential of d̅ 1 in applications.

scholarly journals On the Rank of $p$-Schemes

10.37236/3097 ◽  
2013 ◽  
Vol 20 (2) ◽  
Author(s):  
Fateme Raei Barandagh ◽  
Amir Rahnamai Barghi
Keyword(s):  
Lower Bound ◽  
Prime Number ◽  
Lower Bounds ◽  
Upper Bound ◽  
Upper And Lower Bounds ◽  
Minimum Rank

Let $n>1$ be an integer and $p$ be a prime number. Denote by $\mathfrak{C}_{p^n}$ the class of non-thin association $p$-schemes of degree $p^n$. A sharp upper and lower bounds on the rank of schemes in $\mathfrak{C}_{p^n}$ with a certain order of thin radical are obtained. Moreover, all schemes in this class whose rank are equal to the lower bound are characterized and some schemes in this class whose rank are equal to the upper bound are constructed. Finally, it is shown that the scheme with minimum rank in $\mathfrak{C}_{p^n}$ is unique up to isomorphism, and it is a fusion of any association $p$-schemes with degree $p^n$.

Equational properties of fixed-point operations in cartesian categories: An overview

2019 ◽  
Vol 29 (06) ◽  
pp. 909-925
Author(s):  
Z Ésik
Keyword(s):  
Fixed Point ◽  
Equational Theory ◽  
Continuous Functions ◽  
Equivalence Classes ◽  
Finitely Based ◽  
Additive Structure ◽  
Complete Lattices ◽  
Finite Base ◽  
Language Equivalence ◽  
Context Free

AbstractSeveral fixed-point models share the equational properties of iteration theories, or iteration categories, which are cartesian categories equipped with a fixed point or dagger operation subject to certain axioms. After discussing some of the basic models, we provide equational bases for iteration categories and offer an analysis of the axioms. Although iteration categories have no finite base for their identities, there exist finitely based implicational theories that capture their equational theory. We exhibit several such systems. Then we enrich iteration categories with an additive structure and exhibit interesting cases where the interaction between the iteration category structure and the additive structure can be captured by a finite number of identities. This includes the iteration category of monotonic or continuous functions over complete lattices equipped with the least fixed-point operation and the binary supremum operation as addition, the categories of simulation, bisimulation, or language equivalence classes of processes, context-free languages, and others. Finally, we exhibit a finite equational system involving residuals, which is sound and complete for monotonic or continuous functions over complete lattices in the sense that it proves all of their identities involving the operations and constants of cartesian categories, the least fixed-point operation and binary supremum, but not involving residuals.

The Notion of Transparency Order, Revisited

2020 ◽  
Vol 63 (12) ◽  
pp. 1915-1938 ◽  
Author(s):  
Huizhong Li ◽  
Yongbin Zhou ◽  
Jingdian Ming ◽  
Guang Yang ◽  
Chengbin Jin
Keyword(s):  
Power Analysis ◽  
Equivalence Classes ◽  
Implementation Cost ◽  
Affine Equivalence ◽  
Differential Power Analysis ◽  
Concrete Application ◽  
Substitution Boxes ◽  
Transparency Order ◽  
Definition Of ◽  
Recommended Guidelines

Abstract We revisit the definition of transparency order (TO) and that of modified transparency order (MTO) as well, which were proposed to measure the resistance of substitution boxes (S-boxes) against differential power analysis (DPA). We spot a definitional flaw in original TO, which is proved to significantly affect the soundness of TO. Regretfully, MTO overlooks this flaw, yet it happens to incur no bad effects on the correctness of MTO, even though the start point of this formulation is highly questionable. It is also this neglect that made MTO consider a variant of multi-bit DPA attack, which was mistakenly thought to appropriately serve as an alternative powerful attack. This implies the soundness of MTO is also more or less arguable. Therefore, we fix this definitional flaw and provide a revised definition named reVisited TO (VTO). For demonstrating validity and soundness of VTO, we present simulated and practical DPA attacks on implementations of $4\times 4$ and $8\times 8$ S-boxes. In addition, we also illustrate the soundness of VTO in masked S-boxes. Furthermore, as a concrete application of VTO, we present the distribution of VTO values of optimal affine equivalence classes of $4\times 4$ S-boxes and give some recommended guidelines on how to select $4\times 4$ S-boxes with higher DPA resistance at the identical level of implementation cost.

scholarly journals When is non-trivial estimation possible for graphons and stochastic block models?‡

2017 ◽  
Vol 7 (2) ◽  
pp. 169-181
Author(s):  
Audra McMillan ◽  
Adam Smith
Keyword(s):  
Lower Bound ◽  
Lower Bounds ◽  
Upper Bound ◽  
Upper And Lower Bounds ◽  
Random Networks ◽  
Block Models

Abstract Block graphons (also called stochastic block models) are an important and widely studied class of models for random networks. We provide a lower bound on the accuracy of estimators for block graphons with a large number of blocks. We show that, given only the number $k$ of blocks and an upper bound $\rho$ on the values (connection probabilities) of the graphon, every estimator incurs error ${\it{\Omega}}\left(\min\left(\rho, \sqrt{\frac{\rho k^2}{n^2}}\right)\right)$ in the $\delta_2$ metric with constant probability for at least some graphons. In particular, our bound rules out any non-trivial estimation (that is, with $\delta_2$ error substantially less than $\rho$) when $k\geq n\sqrt{\rho}$. Combined with previous upper and lower bounds, our results characterize, up to logarithmic terms, the accuracy of graphon estimation in the $\delta_2$ metric. A similar lower bound to ours was obtained independently by Klopp et al.

A distance on the equivalence classes of spherical curves generated by deformations of type RI

2018 ◽  
Vol 27 (12) ◽  
pp. 1850066 ◽  
Author(s):  
Yukari Funakoshi ◽  
Megumi Hashizume ◽  
Noboru Ito ◽  
Tsuyoshi Kobayashi ◽  
Hiroko Murai
Keyword(s):  
Lower Bound ◽  
Technical Condition ◽  
Equivalence Classes ◽  
Spherical Curve ◽  
Bound Theorem ◽  
Local Deformations ◽  
Distance Formula

In this paper, we introduce a distance [Formula: see text] on the equivalence classes of spherical curves under deformations of type RI and ambient isotopies. We obtain an inequality that estimate its lower bound (Theorem 1). In Theorem 2, we show that if for a pair of spherical curves [Formula: see text] and [Formula: see text], [Formula: see text] and [Formula: see text] and [Formula: see text] satisfy a certain technical condition, then [Formula: see text] is obtained from [Formula: see text] by a single weak RIII only. In Theorem 3, we show that if [Formula: see text] and [Formula: see text] satisfy other conditions, then [Formula: see text] is ambient isotopic to a spherical curve that is obtained from [Formula: see text] by a sequence of a particular local deformations, which realizes [Formula: see text].

A UNIFIED ALGORITHM FOR THE ESTIMATION AND SCHEDULING OF DATA FLOW GRAPHS

1996 ◽  
Vol 06 (03) ◽  
pp. 287-318 ◽  
Author(s):  
YUAN HU ◽  
BRADLEY S. CARLSON
Keyword(s):  
Lower Bound ◽  
Data Flow ◽  
Optimal Algorithm ◽  
Solution Space ◽  
Computation Time ◽  
Upper And Lower Bounds ◽  
Unified Algorithm ◽  
Data Flow Graphs ◽  
Flow Graphs ◽  
Sharp Lower Bound

A unified algorithm is presented to solve the problem of estimation and scheduling for performance constrained data flow graphs. The algorithm achieves superior results by first computing a lower bound on the number of functional units required to satisfy the performance constraint T, and then scheduling the operations into the best control steps using the lower bound algorithm. The lower bound not only greatly reduces the size of the solution space, but also provides a means to measure the proximity of the final solution to an optimal one. Our algorithm is the first one to use a sharp lower bound estimation technique to direct scheduling. In addition, our unified algorithm can easily be incorporated into a branch-and-bound algorithm to solve the scheduling problem optimally. Since our algorithm computes a sharp lower bound, the computation time of an optimal algorithm can be greatly reduced. Experiments indicate that our scheduling algorithm can produce results very close to the lower bound. For all of the test cases the difference between our upper and lower bounds is not greater than one.

SIMULATIONS OF UNARY ONE-WAY MULTI-HEAD FINITE AUTOMATA

2014 ◽  
Vol 25 (07) ◽  
pp. 877-896 ◽  
Author(s):  
MARTIN KUTRIB ◽  
ANDREAS MALCHER ◽  
MATTHIAS WENDLANDT
Keyword(s):  
Lower Bound ◽  
Lower Bounds ◽  
Finite Automaton ◽  
Finite Automata ◽  
Upper And Lower Bounds ◽  
Unary Languages ◽  
Order Of Magnitude ◽  
Simulation Results ◽  
Special Case ◽  
Nondeterministic Finite Automaton

We investigate the descriptional complexity of deterministic one-way multi-head finite automata accepting unary languages. It is known that in this case the languages accepted are regular. Thus, we study the increase of the number of states when an n-state k-head finite automaton is simulated by a classical (one-head) deterministic or nondeterministic finite automaton. In the former case upper and lower bounds that are tight in the order of magnitude are shown. For the latter case we obtain an upper bound of O(n2k) and a lower bound of Ω(nk) states. We investigate also the costs for the conversion of one-head nondeterministic finite automata to deterministic k-head finite automata, that is, we trade nondeterminism for heads. In addition, we study how the conversion costs vary in the special case of finite and, in particular, of singleton unary lanuages. Finally, as an application of the simulation results, we show that decidability problems for unary deterministic k-head finite automata such as emptiness or equivalence are LOGSPACE-complete.

Sign in / Sign up

Export Citation Format

Share Document