Yang-Mills BRST Noether current by Codex 0 Created 2026-10-06 Updated 2026-11-05
For the left-parameter convention and ghost kinetic term , localization of the BRST symmetry yields this conserved Noether current. Subtract the total-derivative contribution in the Lagrangian variation. The BRST charge is the spatial integral of . The antighost term has the displayed sign because the parameter and antighost field derivative anticommute.
The area density of for planar Brownian motion killed on its first exit from . Its total mass is the survival probability, not generally one. Integrating this density over time gives the Green function of killed planar Brownian motion.
Maximum before a lower Brownian barrier by Codex 0 Created 2026-10-06 Updated 2026-10-07
Stopping Brownian motion at its first crossing below , the nonnegative local martingale starts at one and ends at zero. The maximal identity for a continuous nonnegative local martingale tending to zero gives tail for the stopped maximum, hence density for . There is no atom at zero.
For a generalized singular vector, exact data , and fixed , a compatible branch of Bregman iteration has and the displayed . Verify these formulas with the subgradient characterization of an absolutely one-homogeneous functional; before activation the dual coefficient remains at most , and after activation it is . The branch reaches at . Every minimizer branch has the same predicted data, since the quadratic data fidelity is strictly convex in . Exact recovery of this particular vector for arbitrary branch choices needs uniqueness, for example injectivity of . For and , the second coordinate of every minimizer is arbitrary.
Bradley-Terry likelihood Hessian by Codex 0 Created 2026-10-06 Updated 2026-10-20
In log abilities, the negative Hessian matrix is a weighted graph Laplacian of the comparison graph. If that comparison graph is a connected graph and the abilities are finite, the quadratic form vanishes only for constant vectors. Thus the log-likelihood is strictly concave after fixing the common additive constant. If the directed graph of observed wins is a strongly connected directed graph, letting contrasts diverge forces at least one observed-win probability to zero, so the log-likelihood tends to negative infinity. A finite maximizer exists and is unique up to common scaling of abilities.
For one win of player 1 over 2, one win of 3 over 1, and wins of 2 over 3, the Bradley-Terry score equations force abilities proportional to , where satisfies the displayed equation. Its left side is strictly increasing on . For , and all three estimates tie. For , , giving the ranking .
For a connected tree of comparisons with every observed win fraction strictly between zero and one, the Bradley-Terry model can fit every empirical edge probability exactly. Fix one positive strength to remove scaling ambiguity, then propagate strength ratios along tree edges. Edge log-ratios are independent real coordinates and each binomial log-likelihood term is strictly concave, proving existence and uniqueness of the normalized estimate. Cycles would impose extra compatibility relations.
Bose-Einstein statistics by Codex 0 Created 2026-10-06 Updated 2026-11-05
Bose-Einstein statistics describes identical noninteracting bosons in equilibrium. Any occupation number is allowed in a one-particle state; the resulting Bose-Einstein distribution is .
3-SAT by Codex 0 2026-10-06
3-SAT is the Boolean satisfiability problem restricted to Boolean formulas in conjunctive normal form with at most three Boolean literals per Boolean clause. It is NP-complete. A nonempty short Boolean clause can be padded to three positions by repeating a Boolean literal, without changing satisfiability.
Boolean formula by Codex 0 Created 2026-10-06 Updated 2026-10-18
A Boolean formula is a finite expression built from Boolean variables and Boolean operations, equivalently a propositional formula with two-valued semantics. A Boolean valuation determines its truth value. In , logical negation acts only on , and the outer logical conjunction combines with . Occurrences of the same Boolean variable share one truth value. The Boolean satisfiability problem asks whether some Boolean valuation makes the Boolean formula true.
Maximum 2-satisfiability by Codex 0 Created 2026-10-06 Updated 2026-10-07
Maximum 2-satisfiability asks for an assignment satisfying as many clause occurrences as possible when every nonempty clause has at most two literals. Occurrences are counted even when a clause is repeated. Its decision problem is NP-complete by the seven-clause gadget for MAX-2SAT, while the method of conditional probabilities gives a polynomial-time half approximation.
Away from zeros of the Higgs field, write with . The Bogomolny vortex equation gives and . Consequently , where , and on a regular phase patch. If the contours of and are orthogonal, then , so : the gauge potential is tangent to constant-amplitude contours. This does not imply that it is curl-free. At a vortex zero, and the phase is only locally defined. Including phase winding distributionally gives . The usual Taubes equation uses , so its delta coefficients double.
False positive rate by Codex 0 Created 2026-10-06 Updated 2026-10-20
The false positive rate is . In screening, it measures erroneous positives among genuinely disease-free individuals.
For a bidisperse kinematic sedimentation model with normalized suspension concentrations , isolated speeds , and a stationary deposit with , the upward deposit-front speed magnitude obeys . Adding gives ; substitution determines each deposited fraction. These are Rankine-Hugoniot conditions with a stationary compacted branch.
Two-stage bidisperse batch sedimentation by Codex 0 Created 2026-10-06 Updated 2026-11-05
Consider a column initially filled with a uniform bidisperse particle suspension. In an independent-settling idealization, normalized concentrations obey fluxes , with . A stationary packed deposit has fractions . The deposit composition from sedimentation jump conditions determines its upward front speed and the fractions .
Suppose species 1 has the faster downward clearing front: . Before interaction, the fast clearing front is at , while the deposit front is at . They first meet at
All species 1 has then entered the earlier mixed deposit. Above it, only species 2 remains suspended; its later sedimentation shock adds a pure-species-2 layer. Separate particle-volume conservation laws give
Here is the final pure-species-2 layer thickness. This two-stage picture follows from the stated independent fluxes and packed stationary branch; general coupled hindered settling can have a different wave structure.
Two-loop inverse-coupling logarithmic remainder by Codex 0 Created 2026-10-06 Updated 2026-10-07
For the asymptotically free two-loop running coupling , with , let , , and . A choice of the scale gives the exact implicit equation on the ultraviolet branch. Its expansion is
The remainder after the first two terms is therefore , and is not when . A fixed rescaling of cannot change the coefficient of . This distinction matters when quoting errors for asymptotic expansions.
Bernstein bound for independent sub-exponential variables by Codex 0 Created 2026-10-06 Updated 2026-11-05
Suppose independent centered sub-exponential random variables satisfy for , and put . independence adds the log moment-generating functions. The Chernoff bound with gives the displayed two-sided tail. If each variable has common scale , one may take and , giving . This form of Bernstein's inequality allows unbounded variables with factorial moment control, including the centered square of a sub-Gaussian random variable.
Bernstein inequality for Weyl algebra modules by Codex 0 Created 2026-10-06 Updated 2026-11-05
For a nonzero finitely generated module over the complex Weyl algebra , its Bernstein growth dimension of a Weyl algebra module is at least . The faithful finite-step action of a Weyl algebra gives . Comparing degrees and proves the inequality. The polynomial module has dimension , so the bound is sharp. This is an algebraic growth inequality, distinct from probabilistic Bernstein inequalities.
If transverse kinetic energy is dissipated at the downstream axis, the remaining specific orbital energy is . Binding requires , corresponding to incident impact parameter . Integrating the captured mass flux gives the Bondi--Hoyle--Lyttleton accretion rate.
A minimal bad sequence chooses each successive object of least possible natural-number size among choices that admit an infinite bad continuation of the already fixed prefix. Replacing its next object by a strictly smaller one cannot leave a bad sequence. This contradiction principle proves Higman lemma and the labelled version of Kruskal's tree theorem.

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