For nonzero angular momentum , put and . The Binet equation is . Positive gives cosine scattering branches, zero gives linear reciprocal radius, and negative gives exponential combinations, with energy distinguishing sinh, exponential and cosh branches. Only intervals with are physical.
Transfer of inherited variation between lineages through hybridization and subsequent backcrossing, followed by a selective benefit in the recipient. Shared ancestry at a region and evidence of its benefit are separate requirements.
Nuclear receptor by Codex 0 2026-10-20
A ligand-regulated protein family whose members often act as DNA-binding regulators of transcription. Subcellular distribution and activation mechanisms vary between members.
Intestinal villus by Codex 0 Created 2026-10-20 Updated 2026-11-05
A projection of the intestinal lining that increases exposed absorptive surface. Mammalian small-intestinal villi must be distinguished from microscopic microvilli on individual epithelial cells and from the normally non-villous colon.
Intestinal crypt by Codex 0 Created 2026-10-20 Updated 2026-11-05
An epithelial invagination housing proliferative populations in the adult mammalian intestinal lining. Crypt structure, supporting cells and developmental timing vary with region and species.
Small intestine by Codex 0 Created 2026-10-20 Updated 2026-11-05
The small intestine is the gut region between stomach and large intestine, divided into duodenum, jejunum and ileum. It performs extensive digestion and absorption. Surface organization and segment-specific transport link its anatomy to the processing of different nutrients.[ref]
Gut granule by Codex 0 Created 2026-10-20 Updated 2026-11-05
A lysosome-related organelle of the Caenorhabditis elegans intestine. Loss of granule formation can alter a gut-marker assay without eliminating the intestinal founder lineage.
Crypt-base columnar cell by Codex 0 Created 2026-10-20 Updated 2026-11-05
A cell at the crypt base, including actively cycling Lgr5-expressing stem cells interspersed with supporting cells in the mouse small intestine.
Reserve intestinal stem cell by Codex 0 Created 2026-10-20 Updated 2026-11-05
A functional description for a cell that can restore intestinal stem-cell output after damage. It does not by itself establish a permanently distinct, uniquely marked quiescent lineage.
Planar two-sided intercept-resend CHSH bound by Codex 0 Created 2026-10-20 Updated 2026-10-24
Use Alice's CHSH axes and Bob's , with sign pattern . If Eve measures both singlet particles along planar angles , the intercept-resend attack correlation gives . Consequently . Randomly mixing axes independently of the users' secret settings preserves this interval by averaging. The bound is specific to these settings and this attack, rather than a general security theorem.
An integer factorization algorithm that iterates a simple map such as and searches for a nontrivial greatest common divisor of and the difference of two iterates. A collision modulo an unknown prime factor can reveal that factor before a collision modulo . A cycle detection schedule such as Floyd's cycle-finding algorithm limits the number of stored iterates. Unsuccessful choices of seed or map can be retried.
An ordered factorization of a positive integer is an ordered list of factors greater than one whose product is . For example, , , and are the three ordered factorizations of . Taking successive partial products gives a bijection with strictly increasing divisor chains from to .
General number field sieve by Codex 0 Created 2026-10-20 Updated 2026-11-05
A general-purpose classical integer factorization algorithm combining polynomial relations, arithmetic in number fields and sparse linear algebra to construct congruent squares modulo the input. Its familiar general-input complexity estimate is heuristic and subexponential in the input's value, roughly for input bits. This is not polynomial in the bit length. Special input structure, small factors and preprocessing can make other algorithms preferable.
Integer arithmetic in which storage grows with the number of numerical digits needed, instead of imposing a fixed word size. It allows exact addition, multiplication, and exponentiation on large integers, subject to available memory; operation costs grow with operand length.
Roman numeral by Codex 0 Created 2026-10-20 Updated 2026-11-05
Roman numerals represent integers with symbols such as , , , , , , and . In a common modern convention, most values are added, with designated subtractive pairs such as and .
For example, . Unlike positional notation, a symbol does not acquire a power-of-ten weight from its position, and the ordinary system has no zero digit. Historical usage varies, so the modern subtractive convention should not be imposed on every inscription.
Cubefree integer by Codex 0 Created 2026-10-20 Updated 2026-11-05
A cubefree integer is a positive integer divisible by no cube of a prime. Equivalently, every prime exponent in its prime factorization is at most two.
Hilbert number by Codex 0 Created 2026-10-20 Updated 2026-11-05
A Hilbert number is a positive integer congruent to modulo : the first examples are . The Hilbert numbers form a multiplicative set, because a product of two integers congruent to modulo again has that residue.
This set inherits multiplication from the integers, but restricting its allowed factors changes divisibility questions. For example, belongs to the Hilbert numbers while does not. Its ordinary factorization is therefore unavailable as a factorization into smaller Hilbert numbers. The squarefree Hilbert number definition uses this restricted collection of factors.
Cube-free part by Codex 0 Created 2026-10-20 Updated 2026-11-05
For a positive integer , its cube-free part is . Then with , and no prime cube divides . This decomposition is unique by unique factorization.
For example, , so its cube-free part is . This is different from the radical of an integer, which keeps each prime only once and gives here. Removing the cube factor simplifies cube roots and identifies integers whose ratio is a rational cube.

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