A bifolium is a term used in bookbinding and manuscript studies to refer to a single sheet of paper or parchment that is folded in half to create two leaves (or four pages). The word "bifolium" comes from Latin roots: "bi-" meaning two and "folium" meaning leaf.
A Cartesian oval is a type of mathematical curve that is defined as the locus of points that have a constant ratio of distances to two fixed points, known as foci.
The Hodge bundle is a significant object in the study of algebraic geometry and the theory of Hodge structures. Specifically, the term "Hodge bundle" often refers to a certain vector bundle associated with a smooth projective variety or a complex algebraic variety, particularly when considering its cohomology.
The Graham–Pollak theorem is a result in graph theory that pertains to the relationships between the edges of a complete graph and the configurations of points in Euclidean space. Specifically, it states that for a complete graph on \( n \) vertices, the number of edges that can be embedded in \( \mathbb{R}^d \) (real d-dimensional space) without any three edges crossing is limited.
In mathematics, particularly in topology and algebraic topology, a **classifying space** is a specific type of topological space that allows one to classify certain types of mathematical structures up to isomorphism using principal bundles. The concept is most commonly associated with fiber bundles, especially vector bundles and principal G-bundles, where \( G \) is a topological group.
A symmetric graph is a type of graph that exhibits a certain level of symmetry in its structure. More formally, a graph \( G \) is considered symmetric if, for any two vertices \( u \) and \( v \) in \( G \), there is an automorphism of the graph that maps \( u \) to \( v \).
Metallic bonding is a type of chemical bonding that occurs between metal atoms. In this bond, electrons are not shared or transferred between individual atoms as seen in covalent or ionic bonds. Instead, metallic bonding involves a "sea of electrons" that are free to move around in a lattice of positive metal ions.
The Leibniz operator is a differential operator used in the context of calculus, particularly in the formulation of differentiating products of functions. It is named after the mathematician Gottfried Wilhelm Leibniz, who made significant contributions to the development of calculus.
In topology, the symmetric product of a topological space \( X \), denoted as \( S^n(X) \), is a way to construct a new space from \( X \) that encodes information about \( n \)-tuples of points in \( X \) while factoring in the notion of indistinguishability of points.
Homological stability is a concept in algebraic topology and representation theory that deals with the behavior of homological groups of topological spaces or algebraic structures as their dimensions or parameters vary. The basic idea is that for a sequence of spaces \(X_n\) (or groups, schemes, etc.), as \(n\) increases, the homological properties of these spaces become stable in a certain sense.
The degree of an algebraic variety is a fundamental concept in algebraic geometry that provides a measure of its complexity and size. Specifically, it reflects how intersections with linear subspaces behave in relation to the variety.
John Love is known for his work as a scientist and researcher, particularly in the fields of polymer science and materials chemistry. He has made significant contributions to the understanding and development of novel materials with applications in various industries.

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