Thoralf Skolem (1887–1963) was a Norwegian mathematician known for his significant contributions to mathematical logic, set theory, and model theory. He is best remembered for developing Skolem's paradox and for his work on the foundations of mathematics. One of his notable contributions is in the area of first-order logic and model theory, particularly regarding the completeness of first-order logic and the Löwenheim-Skolem theorem.
Third Normal Form (3NF) is a database normalization standard used to reduce data redundancy and improve data integrity. A database is in Third Normal Form if it satisfies the following conditions: 1. **It is in Second Normal Form (2NF)**: This means that the database is already in First Normal Form (1NF), and all non-key attributes are fully functionally dependent on the primary key.
Scikit-learn by Ciro Santilli 37 Updated 2025-07-16
Examples under python/sklearn
. .venv/bin/activate
pip install sklearn matplotlib seaborn
Pseudo-differential operators (PDOs) are a class of operators that generalize differential operators. They play a crucial role in the analysis of partial differential equations (PDEs), especially in the study of solutions and their regularity properties. PDOs are particularly useful in the context of Fourier analysis and microlocal analysis. ### Definition A pseudo-differential operator is typically defined in terms of its action on test functions through a symbolic calculus.
A singular integral refers to an integral where the integrand has a singularity (point of discontinuity or unbounded behavior) within the domain of integration. The term is often discussed in the context of mathematical analysis and can appear in various forms, including in the theory of functions of a real variable, complex analysis, and the study of partial differential equations.
Outermorphism is a concept in the field of mathematics, specifically in category theory, which deals with the structure and relationships between different mathematical objects. While "outermorphism" is not a standard term widely recognized in mathematics, it may refer to a specific type of morphism that relates to certain structures or transformations in a broader context. In general, the term "morphism" in category theory refers to a structural-preserving map between two objects.
In abstract algebra, particularly in the context of ring theory, a **prime ideal** is a special type of ideal that has important properties related to the structure of rings.
Gin Rummy is a popular card game that has been adapted into various video game formats. The game typically involves two players who try to form sets of cards (three or four cards of the same rank) and runs (three or more cards in sequential order of the same suit). The objective is to reach a certain number of points by being the first to "knock" (end the round) or by forming valid sets and runs with the cards in hand.
Kardboard Kings is a video game that combines elements of simulation and management, where players take on the role of a trading card shop owner. In the game, players manage their store by buying, selling, and trading cards while also interacting with customers and other vendors. The game features a variety of mechanics, including building inventory, customizing the shop, and participating in events like tournaments.
Marion Tinsley was a renowned American checkers (also known as draughts) player, widely regarded as one of the greatest players in the history of the game. Born on April 3, 1929, and passing away on March 2, 1995, Tinsley was particularly known for his mastery of the 8x8 checkers variant. He won numerous national and international titles and was a multiple-time world champion.
AlphaGo is an artificial intelligence program developed by DeepMind Technologies, a subsidiary of Alphabet Inc. (Google's parent company). It is designed to play the complex board game Go, which is known for its deep strategic elements and historically has been considered a major challenge for AI due to its vast number of possible moves and board configurations. AlphaGo made headlines for its ability to defeat some of the world's top Go players, including the reigning world champion Lee Sedol in 2016.
David Silver is a prominent computer scientist known for his work in artificial intelligence, particularly in reinforcement learning and deep learning. He is a principal researcher at DeepMind, a leading AI research company that aims to develop general artificial intelligence. Silver is well-known for his role in the development of AlphaGo, the first AI program to defeat a human champion in the game of Go. This achievement demonstrated significant advancements in machine learning techniques, particularly in using deep neural networks and Monte Carlo tree search.
Geometric graphs are a type of graph in which the vertices correspond to points in some geometric space, and the edges represent some geometric relationships between these points. The arrangement of the vertices in the plane (or in higher dimensions) usually relates to distances, angles, or other geometric properties. Key aspects of geometric graphs include: 1. **Vertex Representation**: The vertices are typically represented by points in a Euclidean space (commonly the 2D or 3D plane).
The Pompeiu problem is a classical question in geometry named after the Romanian mathematician Dimitrie Pompeiu. It involves the relationship between geometric shapes and their properties in relation to points within these shapes.
Inversive distance is a mathematical concept used primarily in the fields of geometry and complex analysis. It is often employed in the context of circles or spherical geometry and is defined in relation to circles. The inversive distance between two circles is defined as the reciprocal of the distance between their respective centers, adjusted for the radii of the circles.
A Steiner chain is a geometric concept that refers to a particular arrangement of circles. Specifically, it is a sequence of circles that are tangent to each other and to some fixed line or point, along with the circles being arranged such that they share a common tangent at the points of tangency.
In mathematics, particularly in the field of differential geometry and topology, a Fréchet surface is not a standard term primarily encountered in classical texts; it might refer to concepts related to Fréchet spaces or Fréchet manifolds, which are more common notions in functional analysis and manifold theory. However, if one were to discuss a "Fréchet surface," it may imply a surface that is modeled or analyzed within the context of Fréchet spaces.
The Gilbert–Pollack conjecture is a hypothesis in the field of combinatorial optimization, specifically regarding the packing of sets in geometric spaces. It posits a relationship between the size of a set and its ability to be packed tightly with respect to certain constraints. Formally, the conjecture deals with the arrangement and packing of spheres in Euclidean space, particularly in three dimensions. It suggests that for any collection of spheres in three-dimensional space, there exists an optimal packing density that cannot be exceeded.
A metric map is a mathematical concept used in various fields such as geometry, topology, and data analysis. It typically refers to a function between two metric spaces that preserves certain properties related to distances. Here’s a brief overview: 1. **Metric Space**: A metric space is a set equipped with a distance function (or metric) that defines the distance between any two points in the set.

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