The Suanpan is a traditional Chinese abacus, an ancient calculating tool used for arithmetic operations such as addition, subtraction, multiplication, and division. It consists of a rectangular frame with rods that hold beads, which can be moved up and down to represent different values. Typically, a Suanpan has two decks of beads: the upper deck contains two beads per rod representing a value of five, while the lower deck has five beads per rod representing a value of one.
The group of rational points on the unit circle refers to the set of points \( (x, y) \) on the unit circle defined by the equation \[ x^2 + y^2 = 1 \] where both \( x \) and \( y \) are rational numbers (numbers that can be expressed as fractions of integers). To describe the rational points on the unit circle, we can parameterize the unit circle using trigonometric functions or with rational parameterization.
A **locally compact abelian group** is a type of mathematical structure that combines concepts from both topology and group theory. Here's a breakdown of what this term means: 1. **Group**: In mathematics, a group is a set equipped with a binary operation that satisfies four fundamental properties: closure, associativity, the existence of an identity element, and the existence of inverse elements.
In group theory, a **locally cyclic group** is a type of group that is, in a certain sense, generated by its own elements in a cyclic manner. More formally, a group \( G \) is said to be locally cyclic if every finitely generated subgroup of \( G \) is cyclic. This means that for any finite set of elements from \( G \), the subgroup generated by those elements can be generated by a single element.
In the context of abelian groups, the term "norm" can refer to a couple of different concepts depending on the specific field of mathematics being discussed. One common usage, particularly in algebra and number theory, is the notion of a norm associated with a field extension or a number field.
A **topological abelian group** is a mathematical structure that combines the concepts of a group and a topology. Specifically, it is an abelian group that has a compatible topology, allowing for the notions of continuity and convergence to be defined in the context of group operations.
In the context of group theory, particularly in the study of abelian groups (and more generally, in the context of modules over a ring), the **torsion subgroup** is an important concept. The torsion subgroup of an abelian group \( G \) is defined as the set of elements in \( G \) that have finite order.
In the context of category theory, a "stub" typically refers to a brief or incomplete article or entry about a concept, topic, or theorem within the broader field of category theory. It often indicates that the information provided is minimal and that the article requires expansion or additional detail to fully cover the topic. This can include definitions, examples, applications, and important results related to category theory. Category theory itself is a branch of mathematics that deals with abstract structures and the relationships between them.
The Brauer–Suzuki–Wall theorem is a result in group theory, specifically in the area of representation theory. The theorem deals with the characterization of certain types of groups, known as \( p \)-groups, and their representation over fields of characteristic \( p \).
In the context of Wikipedia, "Commutative algebra stubs" refers to short articles or entries related to the field of commutative algebra that need expansion or additional detail. A "stub" is generally a brief piece of writing that provides minimal information about a topic, often requiring more comprehensive content to adequately cover the subject. Commutative algebra itself is a branch of mathematics that studies commutative rings and their ideals, with applications in algebraic geometry, number theory, and other areas.
In the context of Wikipedia and other collaborative online encyclopedias, a "stub" refers to a very short article or entry that provides minimal information on a given topic but is intended to be expanded over time. Group theory stubs, therefore, are entries related to group theory—an area of abstract algebra that studies algebraic structures known as groups—that lack sufficient detail, thoroughness, or breadth.
Itô's theorem is a fundamental result in stochastic calculus, particularly in the context of stochastic processes involving Brownian motion. Named after Japanese mathematician Kiyoshi Itô, the theorem provides a method for finding the differential of a function of a stochastic process, typically a Itô process.
A Jaffard ring is a concept in the field of functional analysis and operator theory, named after the mathematician Claude Jaffard. It is related to the study of certain types of algebras of operators, particularly those exhibiting specific algebraic and topological properties.
Auslander algebra is a concept in representation theory and homological algebra, primarily associated with the study of finitely generated modules over rings. The topic is named after the mathematician Maurice Auslander, who made significant contributions to both representation theory and commutative algebra. At its core, the Auslander algebra of a module category is constructed from the derived category of finitely generated modules over a particular ring.
A **cocompact group action** refers to a specific type of action of a group on a topological space, particularly in the context of topological groups and geometric topology. In broad terms, if a group \( G \) acts on a topological space \( X \), we say that the action is **cocompact** if the quotient space \( X/G \) is compact.
The term "complete field" can refer to different concepts depending on the context. Here are a few possible interpretations: 1. **Mathematics (Field Theory)**: In algebra, a "field" is a set equipped with two operations that generalize the arithmetic of the rational numbers. A "complete field" might refer to a field that is complete with respect to a particular norm or metric.
In the context of topology and algebraic topology, the term "component theorem" can refer to several different theorems concerning the structure of topological spaces, graphs, or abstract algebraic structures like groups or rings. However, without a specific area of mathematics in mind, it’s challenging to pin down exactly which "component theorem" you are referring to.
In mathematics, particularly in the study of field theory, a **composite field** is formed by taking the combination (or extension) of two or more fields.
The Baer–Suzuki theorem is a result in group theory that deals with the structure of groups, specifically p-groups, and the conditions under which certain types of normal subgroups can be constructed. The theorem is part of a broader study in the representation of groups and the interplay between their normal subgroups and group actions.
The Brauer–Fowler theorem is a result in the field of group theory, more specifically in the study of linear representations of finite groups. It deals with the structure of certain finite groups and their representations over fields with certain characteristics.

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 5. . 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.
  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