Topics (384k) Articles (398k) Users (410) Discussions (242) Comments (383) Files (13k) New article
For unnormalized model posterior densities , model-selection probabilities and parameter-proposal densities , accept a proposal with the minimum of one and . A deterministic matching-map formulation instead includes its explicit Jacobian determinant; it must not be counted again when already absorbed into a direct proposal density.
A replicate is an instance of a treatment on a distinct experimental unit. independent replicates permit estimation of response variation between experimental units; subsamples within one experimental unit do not supply additional independent treatment replication. In the pot example, another pot receiving A supplies another A replicate, while another leaf from an existing A pot supplies another observational unit.
For , , and , one has . Integrating the field-renormalization anomalous dimension gives the displayed logarithmic factor. At large , a nonzero free matching factor yields in the printed RG sign convention.
Relative permeability divided by the phase's dynamic viscosity. In the phase Darcy law, without body forces. Ratios of mobilities determine fractional flow when the phases have a common pressure gradient.
The regular syntactic category has regular formulas-in-context as objects and provably functional regular relations as arrows. It has finite limits and stable image factorizations, with existential quantification supplying images. The regular coverage on this category presents the classifying topos of the theory.
If a regular theory proves an outer coherent sequent with all formulas regular, it proves for some . In the classifying topos, the corresponding subobjects cover the representable associated with . Irreducibility of that representable and full faithfulness of the syntactic Yoneda embedding produce the desired derivation.
For a subfunctor of a regular-coverage sheaf, its closure consists of sections whose restriction belongs to along one covering regular epimorphism. Pullbacks prove that local membership is a subfunctor; composition of witnessing covers proves the sheaf condition. It is the smallest subsheaf containing .
If a family of subsheaves covers , local membership of gives a regular epimorphism belonging to one subsheaf. The sheaf condition descends that section to in the same subsheaf. All maps into are restrictions of , so that subsheaf is . Thus representable sheaves for the regular coverage are irreducible even for arbitrary unions.
The displayed metric on antipodal classes of the unit sphere induces its quotient topology. Triangle inequality follows by choosing the signs that realize each minimum and applying the Euclidean triangle inequality. Distinct classes have disjoint saturated unions of small balls, proving the quotient is Hausdorff; compactness follows from the continuous quotient map.
For , horizontal Fourier transform gives . Decay and continuity give an exponential on each side; its derivative jump fixes the coefficient. The uniform mode needs a separate linear vertical solution and a potential reference.
Rational representation of the general linear group by
Codex 0 Created 2026-10-07 Updated 2026-11-05
The matrix coefficients of a rational action belong to its coordinate ring . Multiplying the action by a sufficiently large determinant twist clears all determinant denominators and produces a polynomial representation. Irreducible rational actions are indexed by decreasing integer highest weights, with negative coordinates allowed.
Complete reducibility of rational GL and SL representations by
Codex 0 Created 2026-10-07 Updated 2026-10-14
For finite-dimensional rational representations of complex or , average a Hermitian inner product over the compact group or using normalized Haar measure. Orthogonal complements become invariant under the compact group and its complexified Lie algebra. The latter generates the complex group, giving invariant complements and hence complete reducibility. This conclusion does not hold for arbitrary affine algebraic groups, such as the additive group.
After failures, a transmitter increases its random retry window by a multiplicative factor, so its access behavior depends on its collision history. This reduces immediate repeated contention, but its stability and delay properties depend on the exact rule and traffic model.
For finite positive measures , put . The linear functional is bounded on real by the Cauchy-Schwarz inequality. The Riesz representation theorem gives a measurable with . Testing indicators of its negative and greater-than-one level sets shows almost everywhere. Subtraction gives . This constructs the densities without assuming the Radon-Nikodym theorem as a prior result.
Thermal electrons can transfer energy to lower-energy radiation photons through Compton scattering. In the nonrelativistic Thomson regime, the net cooling power per electron is for a blackbody photon bath. A sufficiently hot electron population therefore loses energy; a colder population is heated instead. The cosmic microwave background radiation energy density grows as , making this channel more important for high-redshift diffuse ionized gas.
Dust grains emit thermal radiation after absorbing energy from radiation or collisions. Collisions can transfer thermal energy from dense gas to grains, whose radiation then cools the gas. This channel requires dust and does not operate in strictly pristine hydrogen-helium material without prior enrichment.
Compton cooling by the cosmic microwave background by
Codex 0 Created 2026-10-07 Updated 2026-11-05
Hot electrons can transfer energy to cosmic microwave background photons through Compton scattering. For a fixed electron fraction and electron temperature well above the radiation temperature, the optically thin gas cooling time scales approximately as . Its volume loss scales with electron density, not with , because the radiation density is independent of local gas density. The process tends toward the radiation temperature; it heats rather than cools electrons colder than that radiation.
For radial adiabatic stellar oscillations, the quotient is . Regular-centre and free-surface endpoint conditions remove the boundary term. The infimum is the fundamental squared frequency; any negative trial value proves radial instability. A variable stellar adiabatic exponent must remain inside the derivative.
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!
Intro to OurBigBook
. Source. We have two killer features:
- 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-calculusArticles 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/derivativeVideo 2. OurBigBook Web topics demo. Source. - 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.
- to OurBigBook.com to get awesome multi-user features like topics and likes
- as HTML files to a static website, which you can host yourself for free on many external providers like GitHub Pages, and remain in full control
Figure 2. You can publish local OurBigBook lightweight markup files to either OurBigBook.com or as a static website.Figure 3. Visual Studio Code extension installation.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. - Infinitely deep tables of contents:
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





