Planar algebra is a mathematical structure that arises in the study of operator algebras and three-dimensional topology. It was introduced by Vaughan Jones in the context of his work on knot theory and nontrivial solutions to the Jones polynomial. Planar algebras provide a framework for understanding the relationship between combinatorial structures, algebraic objects, and topological phenomena. In essence, a planar algebra consists of a collection of vector spaces parameterized by non-negative integers, typically with a specified multiplication operation.
Closure operators are a fundamental concept in mathematics, particularly in the areas of topology, algebra, and lattice theory. A closure operator is a function that assigns to each subset of a given set a "closure" that captures certain properties of the subset. Closures help to formalize the notion of a set being "closed" under certain operations or properties. ### Definition Let \( X \) be a set.
A dual polyhedron, also known as a dual solid, is a geometric figure that is associated with another polyhedron in a specific way. For any given convex polyhedron, there exists a corresponding dual polyhedron such that the following properties hold: 1. **Vertices and Faces**: Each vertex of the original polyhedron corresponds to a face of the dual polyhedron, and vice versa.
Term algebra is a branch of mathematical logic and computer science that deals with the study of terms, which are symbolic representations of objects or values, and the operations that can be performed on them. In this context, a term is typically composed of variables, constants, functions, and function applications. Here's a breakdown of some key concepts related to term algebra: 1. **Terms**: A term can be a variable (e.g., \(x\)), a constant (e.g.
In mathematics, particularly in the field of representation theory and algebra, a **Schur functor** is an important concept that arises in the context of polynomial functors. Schur functors are used to construct representations of symmetric groups and to study tensors, modules, and various other algebraic structures.
In category theory, a **product** is a fundamental construction that generalizes the notion of the Cartesian product from set theory to arbitrary categories. The concept of a product allows us to describe the way in which objects and morphisms (arrows) can be combined in a categorical context.
Tits' alternative is a concept from group theory, named after mathematician Jacques Tits. It refers to a criterion for determining whether a given group is either "a linear group" or "a free group." More formally, it involves the classification of certain types of groups based on their actions on vector spaces.
Supersingular primes are an important concept in the context of moonshine theory, which is a branch of number theory that connects two seemingly disparate areas: modular forms and finite group theory. More specifically, moonshine theory is famous for exploring the relationship between certain mathematical structures—the Monster group, the largest of the so-called sporadic simple groups, and modular functions.
A relatively hyperbolic group is a type of group in geometric group theory that generalizes the concept of hyperbolic groups. A group \( G \) is said to be relatively hyperbolic with respect to a collection of subgroups \( \mathcal{P} \) if the asymptotic geometry of \( G \) behaves somewhat like that of a hyperbolic group, but it can include additional structure provided by the subgroups in \( \mathcal{P} \).
The Thurston boundary is a concept from the field of topology, particularly in the study of 3-manifolds. More specifically, it refers to a boundary that arises in the context of 3-dimensional hyperbolic geometry and is used in the classification of 3-manifolds. In general terms, the Thurston boundary often arises in relation to the concept of a compactification of a space.
Henry Wallman is not a widely recognized figure or term in popular culture, academia, or notable events as of my last update in October 2023. It is possible that it could refer to a lesser-known individual, a fictional character, or a specific concept in a niche field.
Rudolf Wille is a German mathematician known for his contributions to formal ontologies and lattice theory. He is particularly recognized for developing the formal concept analysis (FCA), a mathematical method for data analysis and knowledge representation that uses lattice theory to structure and analyze data and relationships. FCA has applications in various fields, including computer science, information science, and social sciences. Through his work, Wille has influenced the study of conceptual structures and the organization of knowledge.
Join dependency is a concept in database theory that is related to the normalization of relational databases, specifically within the context of the fifth normal form (5NF). A join dependency occurs when a relation (table) can be reconstructed by joining multiple smaller relations (subsets of the original relation) based on certain attributes, and this relationship can't be captured simply by functional dependencies.
The Rasiowa–Sikorski lemma is a result in the field of mathematical logic, particularly in set theory and model theory. It provides a criterion for determining whether a certain kind of subset exists in a model of set theory. The lemma is named after the mathematicians Helena Rasiowa and Andrzej Sikorski, who contributed to the field of logic in the mid-20th century.
A harmonious set is a concept that can refer to different things depending on the context in which it is used. Generally, it relates to a collection of elements that work well together or create a pleasing combination. Here are a few interpretations based on different fields: 1. **Mathematics/Logic**: In mathematical contexts, a harmonious set may refer to a set of numbers or elements that exhibit a certain balance or relationship, possibly in terms of averages or ratios.
An **orbital integral** is a concept primarily used in the fields of representation theory and harmonic analysis on groups, especially in the context of Lie groups and algebraic groups. It typically arises in the study of automorphic forms and the trace formula. In general, an orbital integral can be thought of as a tool for integrating a certain class of functions over orbits of a group action.
CAPICOM (Cryptographic API Component Object Model) is a Microsoft technology that provides a simplified interface for developers to implement cryptographic functions in applications. It allows for secure data transactions and is designed to work on Windows platforms. CAPICOM offers functionalities such as: 1. **Digital Signatures**: Allows users to sign documents or data electronically to prove authenticity and integrity. 2. **Encryption and Decryption**: Provides tools to encrypt data so that only authorized users can access it.
In mathematics, specifically in vector calculus, the term "rotor" often refers to the **curl** of a vector field. The curl measures the tendency of a vector field to induce rotation at a point in space.
In abstract algebra, specifically in the study of rings, a **nilpotent ideal** is an ideal such that there exists some positive integer \( n \) for which the \( n \)-th power of the ideal is equal to the zero ideal.
The Go Text Protocol (GTP) is a communication protocol used for connecting Go game software, such as Go engines or game servers, with user interfaces or other software components. It enables the interaction between a Go engine that can play the game and a frontend user interface that displays the game, allowing players to input moves, receive responses, and manage the game state.

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