A **Krull–Schmidt category** is a concept in category theory, particularly in the study of additive categories and their decomposition properties. It is named after mathematicians Wolfgang Krull and Walter Schmidt. In a Krull–Schmidt category, every object can be decomposed into indecomposable objects in a manner that is unique up to isomorphism and ordering.
Pointless topology, also known as "point-free topology," is a branch of topology that focuses on the study of topological structures without reference to points. Instead of using points as the fundamental building blocks, it emphasizes the relationships and structures formed by open sets, closed sets, or more general constructs such as locales or spaces. In typical point-set topology, a topological space is defined as a set of points along with a collection of open sets that satisfy certain axioms.
Simplicial localization is a concept from algebraic topology and category theory that is concerned with the process of localizing simplicial sets or simplicial categories. The process is usually aimed at constructing a new simplicial set that reflects the homotopical or categorical properties of the original set while allowing one to "invert" certain morphisms or objects. ### Background Concepts 1. **Simplicial Sets:** A simplicial set is a combinatorial structure that encodes topological information.
The term "divided domain" can refer to several concepts depending on the context in which it is used. Here are a few interpretations: 1. **Mathematics and Set Theory**: In mathematics, particularly in set theory and analysis, a divided domain may refer to a partitioned set where a domain is split into distinct subdomains or subsets. Each subset can be analyzed independently, often to simplify complex problems or to study properties that hold for each subset.
In ring theory, a branch of abstract algebra, a **primary ideal** is a specific type of ideal that has certain properties related to the concept of prime ideals.
In category theory, a **subterminal object** is a specific type of object that generalizes the notion of a "singleton" in a categorical context. To understand it, let's first define a few key concepts: 1. **Category**: A category consists of objects and morphisms (arrows between objects) that satisfy certain properties (closure under composition, associativity, and identity).
In mathematics, a **topological category** is a category in which the morphisms (arrows) have certain continuity properties that are compatible with a topological structure on the objects. The concept arises in the field of category theory and topology and serves as a framework for studying topological spaces and continuous functions through categorical methods. ### Basic Components: 1. **Objects**: The objects in a topological category are typically topological spaces.
A Waldhausen category is a concept from the field of stable homotopy theory and algebraic K-theory, named after the mathematician Friedhelm Waldhausen. It is used to provide a framework for studying stable categories and K-theory in a categorical context. A Waldhausen category consists of the following components: 1. **Category:** You begin with an additive category \( \mathcal{C} \).
An **analytically irreducible ring** is a concept from algebraic geometry and commutative algebra, closely related to the notion of irreducibility in the context of varieties and schemes.
Hilbert's Syzygy Theorem is a fundamental result in the field of commutative algebra and algebraic geometry that concerns the relationships among generators of modules over polynomial rings. It provides a deeper insight into the structuring of polynomial ideals and their resolutions. In simple terms, the theorem addresses the projective resolutions of finitely generated modules over a polynomial ring.
The concepts of **Hilbert series** and **Hilbert polynomial** arise primarily in algebraic geometry and commutative algebra, particularly in the study of graded algebras and projective varieties. ### Hilbert Series The **Hilbert series** of a graded algebra (or a graded module) is a generating function that encodes the dimensions of its graded components.
A Mori domain is a concept in the field of algebraic geometry, particularly in the study of algebraic varieties and their properties. It is a type of algebraic structure that arises in the context of Mori theory, which is concerned with the classification of algebraic varieties and the birational geometry of these varieties. In more specific terms, a Mori domain is typically a normal, irreducible, and properly graded algebraic domain that satisfies certain conditions related to the Mori program.
In the context of mathematics, particularly in abstract algebra, a **perfect ideal** is a concept that can arise in the theory of rings. However, the term "perfect ideal" is not standard and could be used in various contexts with slightly different meanings depending on the specific area of study.
A quasi-homogeneous polynomial is a type of polynomial that exhibits a certain kind of symmetry in terms of its variable degrees. Specifically, a polynomial \( f(x_1, x_2, \ldots, x_n) \) is called quasi-homogeneous of degree \( d \) if it can be expressed as a sum of terms, each of which has the same "weighted degree".
In algebraic geometry and commutative algebra, a Weierstrass ring is a type of local ring that can be used to study singularities of algebraic varieties. More specifically, it is a particular kind of ring that arises in the context of the Weierstrass preparation theorem. A Weierstrass ring is defined as follows: 1. **Local Ring**: It is a local ring, which means it has a unique maximal ideal.
Win rate is a metric commonly used in various fields such as gaming, sports, finance, and business to quantify the percentage of wins relative to the total number of attempts or events.

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