Symbolic dynamics is a branch of mathematics that studies dynamical systems through the use of symbols and sequences. It focuses on representing complex dynamical behaviors and trajectories in a simplified way using finite or countable sets of symbols. The primary idea in symbolic dynamics is to encode the states of a dynamical system as sequences of symbols. For example, one can take a continuous or discrete dynamical system and map its trajectories onto a finite alphabet (like {0, 1} for binary sequences).
Witt vectors are a construction in mathematics, specifically in the context of algebra and number theory, that generalizes the idea of p-adic integers and provides a way to study vector spaces over finite fields and rings. They were introduced by Ernst Witt in the 1940s and are used primarily in the areas of algebraic geometry, modular forms, and more broadly in the study of arithmetic.
Cayley's mousetrap is a combinatorial structure related to graph theory and enumerates certain types of objects, particularly rooted trees. Named after the British mathematician Arthur Cayley, the term is often used in connection with the enumeration of trees in combinatorial analysis. In a broader sense, Cayley's mousetrap refers to a technique or method in combinatorial enumeration that enables mathematicians to count specific arrangements or structures systematically.
T-theory is a concept in theoretical physics, particularly in the context of string theory and quantum gravity. It is associated with the idea of a particular duality in string theory known as T-duality. T-duality refers to a symmetry between different types of string theories that allows one to relate a string theory with a compactified dimension of a certain size to another string theory with the same dimension compactified at a smaller size.
In graph theory, an **edge cover** of a graph is a set of edges such that every vertex of the graph is incident to at least one edge in the set. In other words, an edge cover is a collection of edges that "covers" all vertices in the graph.
Planarity testing is a computational problem in graph theory that involves determining whether a given graph can be drawn on a plane without any of its edges crossing. A graph is said to be planar if it can be represented in such a way that no two edges intersect except at their endpoints (i.e., at the vertices). The significance of planar graphs lies in various applications across computer science, geography, and network design, among other fields.
An **interval exchange transformation** (IET) is a mathematical concept used in the field of dynamical systems and ergodic theory. It involves a way of rearranging segments of an interval (typically the unit interval \([0, 1]\)) by applying a transformation that is defined by splitting the interval into several subintervals of specific lengths, then permuting those subintervals according to a specific rule.
Surgery theory is a branch of geometric topology, which focuses on the study of manifolds and their properties by performing a kind of operation called surgery. The central idea of surgery theory is to manipulate manifold structures in a controlled way to produce new manifolds from existing ones. This can involve various operations, such as adding or removing handles, which change the topology of manifolds in a systematic manner.
A CW complex (pronounced "C-W complex") is a type of topological space that is particularly useful in algebraic topology. The term "CW" stands for "cellular" and "weak," referring to the construction method used to create such complexes. A CW complex is constructed using "cells," which are basic building blocks, typically in the shape of disks of different dimensions.
In category theory, a "cosmos" is a concept that extends the idea of a category to a more general framework, allowing for the study of "categories of categories" and related structures. Specifically, a cosmos is a category that is enriched over some universe of sets or types, which allows for a more flexible approach to discussing categories and their properties.
The concept of a Giraud subcategory arises in the context of category theory, particularly in the study of suitable subcategories of a given category. Giraud subcategories are named after the mathematician Jean Giraud, and they are important in the study of sheaf theory and topos theory. A Giraud subcategory is typically defined as a full subcategory of a topos (or a category with certain desirable properties) that retains the essential features of "nice" categories.
The Benjamin–Bona–Mahony (BBM) equation is a mathematical model that describes wave propagation in shallow water. It is a simplified equation derived from the full water wave equations, particularly focusing on long waves with small amplitude. The BBM equation incorporates both nonlinearity and dispersion, making it a significant model in the study of wave phenomena.
Airfix is a well-known British manufacturer of plastic model kits, primarily focusing on military vehicles, aircraft, ships, and figures. Founded in 1939 by Nicholas K. Churchill, the brand gained popularity for its detailed and historically accurate models that cater to hobbyists and collectors of all ages. Airfix kits come in various sizes and complexity levels, making them accessible for both beginners and experienced model builders.
Gaetano Fichera is not widely known and may refer to multiple individuals, given that it is a personal name. However, the most notable Gaetano Fichera is an Italian mathematician recognized for his work in the fields of analysis and partial differential equations. He has published various papers and contributed to the mathematical community.
As of my last knowledge update in October 2023, Alexander Braverman is a prominent mathematician known for his work in the field of mathematical logic and computability theory. He has contributed significantly to areas such as effective model theory, algorithmic randomness, and the foundations of mathematics. Braverman has published numerous research papers and has been involved in various academic activities, including teaching and supervising students.
ALFRED (Italian acronym for "Advanced Lead-cooled Fast Reactor for Electricity and Decarbonization") is a conceptual design for a nuclear reactor that utilizes lead as the primary coolant and operates as a fast neutron reactor. It is part of ongoing research and development efforts in advanced nuclear technologies, particularly focusing on sustainability, safety, and efficiency in power generation.
Ali Aliev is a physicist known for his work in the field of nanophysics and quantum optics. He has made significant contributions to the understanding of nanostructures, especially in relation to their electronic and optical properties. His research often involves exploring new materials and structures at the nanoscale, with potential applications in various fields such as electronics, photonics, and material science.

Pinned article: Introduction to the OurBigBook Project

Welcome to the OurBigBook Project! Our goal is to create the perfect publishing platform for STEM subjects, and get university-level students to write the best free STEM tutorials ever.
Everyone is welcome to create an account and play with the site: ourbigbook.com/go/register. We belive that students themselves can write amazing tutorials, but teachers are welcome too. You can write about anything you want, it doesn't have to be STEM or even educational. Silly test content is very welcome and you won't be penalized in any way. Just keep it legal!
We have two killer features:
  1. topics: topics group articles by different users with the same title, e.g. here is the topic for the "Fundamental Theorem of Calculus" ourbigbook.com/go/topic/fundamental-theorem-of-calculus
    Articles of different users are sorted by upvote within each article page. This feature is a bit like:
    • a Wikipedia where each user can have their own version of each article
    • a Q&A website like Stack Overflow, where multiple people can give their views on a given topic, and the best ones are sorted by upvote. Except you don't need to wait for someone to ask first, and any topic goes, no matter how narrow or broad
    This feature makes it possible for readers to find better explanations of any topic created by other writers. And it allows writers to create an explanation in a place that readers might actually find it.
    Figure 1.
    Screenshot of the "Derivative" topic page
    . View it live at: ourbigbook.com/go/topic/derivative
  2. local editing: you can store all your personal knowledge base content locally in a plaintext markup format that can be edited locally and published either:
    This way you can be sure that even if OurBigBook.com were to go down one day (which we have no plans to do as it is quite cheap to host!), your content will still be perfectly readable as a static site.
    Figure 2.
    You can publish local OurBigBook lightweight markup files to either https://OurBigBook.com or as a static website
    .
    Figure 3.
    Visual Studio Code extension installation
    .
    Figure 4.
    Visual Studio Code extension tree navigation
    .
    Figure 5.
    Web editor
    . You can also edit articles on the Web editor without installing anything locally.
    Video 3.
    Edit locally and publish demo
    . Source. This shows editing OurBigBook Markup and publishing it using the Visual Studio Code extension.
    Video 4.
    OurBigBook Visual Studio Code extension editing and navigation demo
    . Source.
  3. https://raw.githubusercontent.com/ourbigbook/ourbigbook-media/master/feature/x/hilbert-space-arrow.png
  4. Infinitely deep tables of contents:
    Figure 6.
    Dynamic article tree with infinitely deep table of contents
    .
    Descendant pages can also show up as toplevel e.g.: ourbigbook.com/cirosantilli/chordate-subclade
All our software is open source and hosted at: github.com/ourbigbook/ourbigbook
Further documentation can be found at: docs.ourbigbook.com
Feel free to reach our to us for any help or suggestions: docs.ourbigbook.com/#contact