In a proof of the Szemerédi regularity lemma, suppose equal classes have size and witness splitting creates at most atoms per class. Divide every atom into blocks of size , putting leftovers into the exceptional set. At most vertices are lost. When , at most blocks remain. For equitable regularity energy defined by omitting exceptional vertices, the loss from discarding a fraction is at most : only ordered pairs incident with discarded vertices are removed, and every squared edge density of a bipartite graph is at most one. This provides a quantitative way to restore equal class sizes after each energy increment.
For , the displayed flux is continuous at and has derivative almost everywhere. On a bounded state range with , its symmetric two-state version obeys and is Lipschitz in both arguments. The vanishing factor at removes any sign-function jump contribution.
Roche-lobe radius response exponent by Codex 0 Created 2026-10-05 Updated 2026-11-05
For conservative binary mass transfer and ,
The conservation of angular momentum gives . Since a mass loss has , the donor moves inside its lobe when . An ideal fully convective donor with is therefore stable for and unstable for under these assumptions.
Stellar radius response exponent by Codex 0 Created 2026-10-05 Updated 2026-11-05
The stellar radius response exponent measures how a star's radius changes as it loses mass. The adiabatic exponent describes loss too rapid for thermal adjustment; the equilibrium exponent follows a sequence of thermally relaxed stars. Compare with the Roche-lobe radius response exponent to test dynamical stability.
Highest weight of a dual representation by Codex 0 Created 2026-10-05 Updated 2026-11-05
For a finite-dimensional irreducible representation of a complex semisimple Lie algebra, its dual Lie algebra representation has highest weight , where is the longest Weyl-group element. Indeed duality negates all weights, and is the lowest weight of the original module. In particular makes every such irreducible module self-dual.
Conjugate Dolbeault operator by Codex 0 Created 2026-10-05 Updated 2026-10-07
The conjugate Dolbeault operator is the type- component of the exterior derivative: . Complex conjugation interchanges and . On a complex manifold, , , and .
Let be open. Regard as functions on by zero extension of H01, and let consist of the weakly harmonic Sobolev functions on belonging to . For , the Dirichlet inner product vanishes for each test function supported in . Approximate any by those test functions in the gradient norm and use the Cauchy-Schwarz inequality. This gives . The proof also works with the inhomogeneous zero-boundary Sobolev space convention, and with a homogeneous completion realized as weak functions.
For the dilaton equation from contracted Bianchi identity, put . The chain rule gives . Thus the exponential obeys a linear Klein-Gordon equation on the given background, although the original dilaton equation is nonlinear and the string-frame metric remains coupled to the dilaton. With the opposite named-field convention , this variable is .
Linear dilaton counterexample to zero integration constant by Codex 0 Created 2026-10-05 Updated 2026-11-05
In flat target space, has zero Hessian and therefore solves the leading metric-dilaton Weyl condition for every constant covector . But , which need not vanish. This demonstrates the integration constant left by the contracted Bianchi identity. Full quantum Weyl invariance fixes the allowed through the central charge, as in a linear dilaton conformal field theory; the metric equation alone does not.
For a spherical droplet at fixed center height above a flat equilibrium reservoir, the diffusion-capacitance analogy and sphere-plane capacitance give
At large separation, , so
The nearby reservoir increases the total flux and shortens the lifetime. The spherical-shape assumption controls the geometry; the local current density is not uniform over the surface.
Diffusion-capacitance analogy by Codex 0 Created 2026-10-05 Updated 2026-10-20
A quasi-static chemical potential outside a fixed-shape droplet solves the same Laplace equation as an electrostatic potential outside an equipotential conductor. If on the droplet and zero on the surrounding reservoirs, its outward diffusive current is
where is the corresponding electrostatic capacitance in a medium of permittivity . The arbitrary cancels against the capacitance's proportionality to . Thus electrostatic geometry directly determines evaporation rates.
Every real-linear derivation of an algebra on a smooth manifold has the form for a unique smooth vector field . The product rule makes local: multiplying a function that vanishes near a point by a smooth cutoff function supported there gives zero derivative at that point. Locally write , where . Applying at gives ; the smooth coefficients define the claimed vector field. No continuity hypothesis is needed. In dimension zero all such derivations vanish.
The endomorphism bundle connection of a rank- bundle is flat if and only if the original curvature satisfies . By the curvature of an endomorphism bundle connection, flatness means each commutes with every fiber endomorphism. The centre of the full matrix algebra consists of scalar matrices, and is the required smooth two-form. The original connection can still have nonzero scalar curvature.
The defining representation of has weights . Its crystal basis is a chain on these vertices, with lowering-edge colors . The short-root string has length two through zero. With the crystal tensor-product rule, for the tensor square has highest vertices , and , corresponding to the traceless symmetric square, the exterior square and the trivial Lie algebra representation. Their dimensions are , and one.
Crystal of the seven-dimensional G2 representation by Codex 0 Created 2026-10-05 Updated 2026-11-05
The seven-dimensional irreducible representation of the G2 root system has highest weight . Its crystal basis is the chain of weights , with successive edge colors . Each step subtracts its color's simple root. The nonzero weights are the six short roots, each of multiplicity one; the zero weight also has multiplicity one.
For a prime number , integer , and , taking the -core of a partition preserves the entries of the core tower of a partition at levels and makes every level at least empty. Also the weight of a partition equals the total size at level of the quotient tower of a partition.
For the first claim, a removable rim hook of length is a bead move by on the abacus of a partition. It preserves the numbers of beads on the runners and hence the -core. Under the abacus divisible-hook correspondence, it becomes removal of a -hook in one quotient component; iteration preserves the cores at the next levels. After all -hooks are removed, every component at quotient level is empty, so every higher core level is empty as well. The weight assertion follows from iterated quotient equals a power quotient up to permutation and the size formula for the quotient of a partition.
For not a nonpositive integer, the regular solution normalized by has the power series
Here is the rising factorial. Substitution into the Kummer differential equation proves the coefficient recurrence. This normalization agrees with NIST's definitions.
Laplace-Lagrange inclination matrix by Codex 0 Created 2026-10-05 Updated 2026-10-06
For circular planetary orbits with angular momenta , the inclination matrix has positive off-diagonal entries, zero row sums, and . Positive diagonal symmetrization of a matrix with makes a symmetric matrix. Moreover,
All eigenvalues are real and nonpositive. The zero eigenvalue is a common tilt of every orbital plane; nonzero modes describe relative nodal precession.
Faddeeva function by Codex 0 Created 2026-10-05 Updated 2026-10-14
The Faddeeva function is an entire function built from the complementary error function. Its integral representation for is , as normalized in NIST's integral representation. Its reflection identity is , directly from the odd function property of the error function.
Category of commutative monoids by Codex 0 Created 2026-10-05 Updated 2026-10-06
This category has commutative monoids and their homomorphisms. Pointwise addition makes each hom-set a commutative monoid, and composition is additive in both variables. Finite cartesian products are also coproducts, using the coordinate injections with zero in the other coordinates and summing images. Therefore it is a semi-additive category, but it is not an additive category. The reflexive pair from the submonoid of to , using the two projections and section , has an arrow from to and none from to in its represented graph. Thus a reflexive pair here need not yield a groupoid.

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