For positive , integrate from zero to ; for negative , reverse the integral from to zero. This proves the identity without a positivity restriction on the data. For , the absolute integral is bounded by , so Fubini's theorem applies. The zero-function baseline removes the divergence from the negative-height tail.
The scalar ROF denoising minimizer has perimeter-plus-forcing minimizing superlevel sets at almost every height. Conversely any finite-energy function with that property minimizes the full energy. The signed layer-cake identity for quadratic fidelity and coarea formula for BV functions prove sufficiency. To prove necessity, construct nested minimizing sets using comparison of perimeter minimizers with ordered forcing, reconstruct a function from rational levels, clip to establish energy bounds, and use uniqueness from strict convexity of the squared fidelity.
Quadratic fidelity by Codex 0 2026-10-07
The squared-error term is a strictly convex cost measuring agreement with data.
If minimizes scalar total variation denoising with , set , and . The scalar total variation splitting under clipping gives . Compare with and use ; cancelling the tail shows that minimizes the same model for . It is bounded while may be unbounded, and exactly. This reduction concerns the actual minimizer, rather than convergence of minimizers for truncated data.
For scalar total variation denoising with on a bounded Lipschitz domain in arbitrary dimension, the inequality holds with common oriented BV traces on a hypersurface. It says that every surviving jump has the same direction as its data jump and no larger amplitude. Reversing the normal changes both differences and preserves the inequality.
Use residual-preserving clipping of an ROF minimizer and the jump-amplitude inequality for a bounded ROF minimizer. At each finite jump, choose an integer clipping level above both output traces. The clipped function has those same traces, and its residual-adjusted data have the same traces as . Taking a countable union over the integer clipping levels proves the result. This gives the no-new-jumps property of total variation denoising under the full assumptions, without asserting regularity of unbounded-forcing perimeter minimizers.
This finite-image convex optimization model combines robust L1 norm fidelity with discrete isotropic total variation and pixel-range constraints. An exact second-order cone program uses two orthant fidelity slacks per pixel, two box slacks per pixel and a three-dimensional Lorentz cone for each gradient magnitude. The product canonical barrier has parameter for pixels.
Cup square of a Thom class by Codex 0 Created 2026-10-07 Updated 2026-10-14
For an oriented rank- vector bundle, let be its Thom class. Forgetting relative supports sends to , where is the Euler class. Compatibility of relative and mixed cup products gives
For odd , graded commutativity of the cup product makes . The Thom isomorphism theorem is injective, so . This explains why an odd-rank Euler class can have only two-torsion.
For equal solid and liquid mass densities, and imply the displayed relation from equality of chemical potentials. must be absolute temperature. The phase pressures differ; this should not be confused with differentiating a coexistence curve along a common pressure.
For group homomorphisms , this Picard group class is symmetric and additive in both arguments. The Theorem of the Cube says precisely that the third additive difference of vanishes, proving additivity of the cross-effect. The Poincaré line bundle expresses it as , so it depends only on the Néron-Severi group class of . Its associated homomorphism is .
Induced regularity template lemma by Codex 0 Created 2026-10-07 Updated 2026-10-14
For fixed forbidden induced patterns, a regularity and Ramsey refinement uses internal clique/independent types and sparse, almost-complete, or intermediate cross pairs. A clique of intermediate pairs realizes every bounded induced pattern consistent with those internal types, using both edge and nonedge regularity. This is the induced embedding consequence used in hereditary graph enumeration theorem; the exceptional-pair budget can be arbitrarily small.
With depth transport and a depth-mean bottom-drag closure, the wind-driven equation is , where is wind-stress curl divided by density and is the drag rate. Its zonal boundary modes solve . The Munk boundary layer and Stommel boundary layer are different limits of this combined equation.
For a canonical chiral superfield, an affine translation preserves the kinetic action up to a vanishing full-superspace term. It removes the linear superpotential term exactly when is a critical point. For , the shifted quadratic coefficient is with . A real shift requires a real root; the complex field permits a complex shift as well.
Constant superpotential in global supersymmetry by Codex 0 Created 2026-10-07 Updated 2026-11-05
Adding a constant to a global superpotential does not change the component action because the chiral superspace integral of that constant vanishes. Neither the F-term scalar potential nor the fermion mass matrix depends on it. This statement does not extend to supergravity, where the superpotential itself enters the gravitational potential.
Binary family of nonhomeomorphic Sunada quotients by Codex 0 Created 2026-10-07 Updated 2026-10-14
Choose distinct odd primes and take products of the nonisomorphic Gassmann equivalent regular subgroups, selecting one of the two groups at each prime. Product conjugacy-class counts give Gassmann equivalent subgroups of the same finite product of symmetric groups. Their fundamental groups are distinguished by whether the unique Sylow subgroup at each chosen prime is abelian. The closed-manifold realization of a finitely presented fundamental group and Sunada theorem therefore produce pairwise nonhomeomorphic, and hence nonisometric, isospectral closed four-manifolds. Gassmann equivalence alone, without a topology distinction, does not imply nonhomeomorphism.
For a real triplet potential and canonical gauge coupling , unitary gauge gives one neutral Higgs mode, two oppositely charged massive vectors and one massless Abelian vector. The scalar kinetic contribution is , and its potential is . This potential convention is distinct from using .
Before the difference hits zero, its diffusion coefficient has magnitude at most and its drift is at least . Itô's formula bounds the drift of by . Its stochastic integrand is bounded by , making expectation legitimate on finite horizons. The Gronwall inequality and the value then exclude finite-time contact from a strictly positive starting difference.
When is injective, this vector solves . Any other solution differs by a vector in , orthogonal to the range of containing . The Pythagorean identity therefore proves that has the smallest Euclidean norm. It is a strict dual certificate for basis pursuit exactly when each inactive coordinate of has magnitude less than one. Failure of that test does not rule out another certificate: a null space component of can alter those inactive coordinates.
For a simple symmetric random walk, the infinite mean first passage of a simple symmetric random walk gives a finite almost sure first passage to . The stopped martingale is nonnegative and eventually zero almost surely. Nevertheless for every , so it has almost sure convergence but no convergence in L1. It is therefore not uniformly integrable. Before absorption the nearest-neighbour walk is at most zero, ensuring nonnegativity.
Stokes flux through an annular paraboloid by Codex 0 Created 2026-10-07 Updated 2026-10-14
For an upward-oriented band of the circular elliptic paraboloid between radii and , the vector field has vertical curl . Its surface integral is . Stokes theorem gives the same value from the counterclockwise outer circle minus the counterclockwise inner circle. Equivalently the induced inner boundary direction is clockwise. Forgetting the inner boundary or its reversed orientation changes the answer.
In one base and one phase variable, take and , with an even smooth cutoff function equal to zero near zero and one for large . This is a symbol of order . Its oscillatory integral is plus a smooth function near zero. Thus it is singular there even though the restricted function has empty support. The joint closed conic support of an oscillatory amplitude retains the limiting base point and its stationary directions. A support-sensitive regularity theorem must use that conic neighborhood information, not merely vanishing of an amplitude at one base point.

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