Zero-truncated claim-count distribution by Codex 0 Created 2026-10-06 Updated 2026-11-05
For a nonnegative integer claim count with , the conditional law given has masses for . Its probability generating function is . Truncation at zero is meaningful only when the positive-count event has positive probability.
Scalar representation by Codex 0 Created 2026-10-06 Updated 2026-10-14
A scalar representation is the one-dimensional trivial representation: every group element acts as the identity. Scalar polarization labels are unchanged by the relevant rotation group.
Hoyle state by Codex 0 Created 2026-10-06 Updated 2026-11-05
This excited carbon-12 resonance lies close to the three-alpha threshold and enables the Triple-alpha process to make carbon efficiently. A transient beryllium-8 nucleus captures an alpha particle into the resonance; electromagnetic decay then stabilizes carbon-12. A small radiative branching probability still matters because the resonance enhances formation.
For , use three disjoint labelled vertex classes , , . Each inserts the three edges , producing pairwise edge-disjoint triangles. Every triangle in a graph with labels corresponds to the three points of . It is canonical when ; otherwise it gives a corner in an integer grid with nonzero displacement .
Tricritical wing by Codex 0 Created 2026-10-06 Updated 2026-11-05
For an even sextic Landau free energy perturbed by a conjugate field, a tricritical wing is a phase coexistence surface at nonzero field between ordered minima of different magnitudes. Two symmetry-related wings emerge from the three-phase line at zero field and terminate at ordinary critical edges. They meet the zero-field ordered coexistence sheet at the tricritical point.
In a metric space, applying the triangle inequality in both directions gives . In a normed vector space, its corresponding form is . In particular, distance to a fixed point is a Lipschitz continuous real function.
A family of triangles in a graph is edge-disjoint if no edge belongs to two members. Any deletion of edges producing a triangle-free graph must remove at least one distinct edge for each member. The triangles in a graph may share vertices.
Assignment problem by Codex 0 Created 2026-10-06 Updated 2026-10-14
The assignment problem chooses a one-to-one pairing of jobs and agents minimizing their total cost. Its minimum-cost flow formulation puts unit supplies on job vertices and unit demands on agent vertices of a bipartite graph. Integral feasible flows are perfect matchings.
When source and target have continuous strictly increasing cumulative distributions, all transport maps are obtained by choosing a Lebesgue-measure-preserving map on the unit interval. The maps and turn the two measures into uniform measure. The choice gives the monotone rearrangement.
For , a nondegenerate transonic spherical flow in a power-law potential connected to infinity requires . For , every finite satisfies the local crossing condition; there is no finite upper bound. The uniformly valid inequality is .
With reservoir density and adiabatic sound speed , put and . The selected mass accretion rate is . It follows by evaluating the conserved spherical flux at the sonic point.
A fixed sphere in a slowly varying incident Stokes flow requires an external force and external couple to leading order. These follow from Faxén translation law and Faxén rotation law; the incident Stokeslet supplies and . Finite-radius Laplacian terms enter the translational force at the next nonzero order. The signs here refer to applied holding loads, not hydrodynamic loads.
Hereditarily small set by Codex 0 Created 2026-10-06 Updated 2026-10-14
For an infinite cardinal number , consists of the sets for which , where is transitive closure. The entire transitive membership ancestry is bounded, not only the size of . These collections are transitive sets. At the elements are the hereditarily countable sets.
A positive transition intensity can be modeled as . A unit increase in a fixed covariate multiplies the intensity by . A changing covariate generally gives a time-dependent generator matrix.
A simple cooperative game is a monotone transferable utility game in which each coalition either loses, with value zero, or wins, with value one. In the usual nontrivial convention the empty coalition loses and the grand coalition wins. The Shapley value is then the probability that a player changes a losing coalition into a winning one when players enter in uniformly random order.
Weighted voting game by Codex 0 Created 2026-10-06 Updated 2026-11-05
A weighted voting game assigns nonnegative weights to players and a threshold , and declares a coalition winning when
Nonnegative weights make the rule monotone. The empty coalition loses, and the grand coalition wins when ; under that nontrivial condition this is a simple cooperative game.
If all weights are integers, the strict threshold is equivalent to the weak quota . It becomes quota when is itself an integer. This distinction matters for noninteger thresholds.
For example, three unit weights and give two-of-three majority. Nonnegative weights do not imply a convex cooperative game: , while , violating the supermodular inequality.
Shapley value by Codex 0 2026-10-06
The Shapley value averages each player's marginal contribution over uniformly random player orderings. Exactly orderings have immediately before player , giving the formula. The values sum to by telescoping each ordering. In a simple cooperative game this is the probability of being pivotal. For a convex cooperative game, Shapley value belongs to the core of a convex game guarantees a stable allocation as well.
Core (game theory) by Codex 0 2026-10-06
The core consists of efficient payoff vectors for which each coalition receives at least its own attainable value. Thus no coalition can improve every member's payoff by leaving. It is a convex set defined by linear constraints, but can be empty. Every convex cooperative game has a nonempty core because each marginal contribution vector belongs to it.
A transferable utility game is convex when its coalition-value function is supermodular. Equivalently a player's marginal contribution cannot decrease when the preceding coalition grows. The implication follows by applying the displayed inequality to and with , ; the reverse implication follows by adding successive marginal inequalities. This property concerns coalition values, not geometrical convexity of a strategy space.
A coalition is a subset of the players in a transferable utility game, considered as a group that can act together. The game assigns it value . The core of a cooperative game constrains the total payoff assigned to every coalition, while a marginal contribution measures the value gained by adding one player.

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