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Understanding Uniform Distribution Through Lattices

Learn how lattices can create uniform distributions in various dimensions.

― 5 min read


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Table of Contents

Uniform distribution is a significant concept in mathematics and many applied fields. It deals with how points can be arranged or spread out within a specific space, such as a unit hypercube or a sphere. This article explains how Sequences of points can be constructed to achieve uniform distribution by using Lattices.

What Are Lattices?

A lattice is a structured arrangement of points in space. Think of a grid where points are spaced evenly apart. These points often belong to a set defined by certain rules or parameters. The primary goal when working with lattices is to create point sets that are as evenly distributed as possible across a given area.

Sequences and Their Importance

In the context of uniform distribution, sequences are ordered lists of numbers or points. A well-known type of sequence used in distribution problems is the van der Corput sequence. These sequences can help achieve uniform distribution in various settings, including higher dimensions.

Discrepancy Functions: Measuring Uniformity

One way to assess how well points are distributed is through discrepancy functions. These functions measure the deviation from a perfectly uniform distribution. Essentially, they provide a way to quantify how "non-uniform" a given arrangement is. A low discrepancy value indicates that a sequence of points is close to being uniformly distributed.

The Role of Digit Sums

Digit sums are a special aspect of how numbers can be expressed. The digit sum of a number is simply the total of its digits. For example, the digit sum of the number 123 is 1 + 2 + 3 = 6. In this context, digit sums can be used to analyze and compare different sequences, particularly in relation to their discrepancy.

Applications in Higher Dimensions

While the basic ideas and sequences often start in two or three dimensions, the work can be extended to higher dimensions. This extension allows for the examination of how well points fill out spaces like a hypercube or a sphere. The techniques used in two dimensions can often be adapted and applied in more complex spaces.

Two-Sphere Applications

The study of uniform distribution also includes arrangements on a two-dimensional sphere. This is relevant in many fields, including computer graphics, astronomy, and even gaming. By applying lattice-based approaches, it is possible to create point distributions on a sphere that maintain low discrepancy.

Constructing Sequences with Self-Similarity

A notable feature of some sequences is self-similarity. This means that parts of the sequence resemble the whole sequence when zoomed in. This property can make it easier to generate sequences that maintain uniform distributions. In practice, this can lead to more efficient algorithms for generating points.

Perturbed Lattices: An Advanced Concept

Sometimes, regular lattices can be modified, or "perturbed," to achieve better distribution. A perturbed lattice takes the basic structure of a lattice but adjusts the points slightly. This adjustment can often lead to improved results in terms of how uniformly the points spread out in the space.

The Benefits of Using Sequences

Using sequences for uniform distribution has advantages over other methods. For one, sequences can be easier to compute and manipulate. They allow for finer control over the distribution process. Specifically, mathematical constructs like polynomial sequences can be used effectively to produce well-distributed points across different spaces.

Ensuring Valid Translations

In constructing sequences, valid translations (shifting the sequences without overlap) become crucial. These transformations make it easier to analyze how points interact with one another and ensure that the arrangement of points remains uniform throughout the space.

Monte Carlo Methods and Numerical Applications

Monte Carlo methods are statistical techniques used to approximate numerical results through random sampling. Understanding how to generate points that are uniformly distributed is vital for making the most out of these numerical applications. This allows researchers and practitioners to achieve better accuracy in their simulations and calculations.

Probability and Distribution

Point distributions can also be viewed through the lens of probability. How likely is it that a point falls within a certain area? The goal is to create arrangements where this probability is uniform. Using lattice structures helps in achieving this arrangement.

Future Directions

As research continues in this area, it will likely open new avenues in both theoretical and applied mathematics. There are many potential applications in fields such as computer science, physics, and engineering, where uniform distributions are critical for modeling and simulations.

Summary

In summary, uniform distribution through lattices involves the careful construction of sequences of points. Through the use of discrepancy functions, digit sums, and other mathematical tools, it is possible to assess and improve the uniformity of distributions in various dimensions and shapes. This work has far-reaching implications across different scientific domains, from improving algorithms in computer graphics to enhancing simulations in physics and engineering. The exploration of distributions on spheres and hypercubes continues to be a vibrant area of research, pushing the boundaries of what is possible in mathematical modeling and applications.

Original Source

Title: Uniform distribution via lattices: from point sets to sequences

Abstract: In this work we construct many sequences $S=S^\Box_{b,d}$, or $S=S^\boxplus_{b,d}$ in the $d$--dimensional unit hypercube, which for $d=1$ are (generalized) van der Corput sequences or Niederreiter's $(0,1)$-sequences in base $b$ respectively. Further, we introduce the notion of $f$-sublinearity and use it to define discrepancy functions which subsume the notion of $L^p$-discrepancy, Wasserstein $p$-distance, and many more methods to compare empirical measures to an underlying base measure. We will relate bounds for a given discrepancy functions $\mathscr{D}$ of the multiset of projected lattice sets $P(b^{-m}\mathbb{Z}^d$), to bounds of $\mathscr{D}(Z_N)$, i.e. the initial segments of the sequence $Z=P(S)$ for any $N\in\mathbb{N}$. We show that this relation holds in any dimension $d$, for any map $P$ defined on a hypercube, and any discrepancy function as introduced in this work for which bounds on $P(b^{-m}\mathbb{Z}^d+v$) can be obtained. We apply this theorem in $d=1$ to obtain bounds for the $L^p$--discrepancy of van der Corput and Niederreiter (0,1) sequences in terms of digit sums for all $0

Authors: Damir Ferizović

Last Update: 2023-12-31 00:00:00

Language: English

Source URL: https://arxiv.org/abs/2308.13297

Source PDF: https://arxiv.org/pdf/2308.13297

Licence: https://creativecommons.org/licenses/by-sa/4.0/

Changes: This summary was created with assistance from AI and may have inaccuracies. For accurate information, please refer to the original source documents linked here.

Thank you to arxiv for use of its open access interoperability.

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