Topics (384k) Articles (398k) Users (410) Discussions (242) Comments (383) Files (13k) New article
For a positive claim and , the tail integral formula for moments gives the displayed expression. In particular the first moment is and the raw second moment is . If the claim law has a density, capping adds an atom of a measure at with mass .
Total variance stationary condition for excess of loss by
Codex 0 Created 2026-10-07 Updated 2026-11-05
For positive claim sizes with finite second moment in a compound Poisson distribution aggregate of parameter , the two excess of loss reinsurance payouts are and . The derivative of their total aggregate variance is . Thus the displayed condition characterizes stationarity. When the tail probability is positive it says that the retention equals the mean residual life. Global minimality requires an additional sign or comparison argument.
One exact parity query determines whether the first two bits agree. If they agree, a second query reads one of them; otherwise it reads the third bit. Those values respectively determine the three-bit majority function. The matching lower bound follows from its degree-three multilinear polynomial.
Suppose a function has least period and distinct values on distinct period cosets. Two independent Fourier samples have the form with uniform . The displayed candidate is , so exact recovery occurs when no prime divisor of divides both residues. The Chinese remainder theorem gives probability , using the Euler product. Unlike a single-sample coprimality probability, this bound is uniformly greater than one half. A candidate-period test makes successful recovery heralded when such a test is available.
For and , integrate over to obtain the displayed identity. Tonelli theorem then expresses the moment of a nonnegative random variable as the same integral of expected call payoffs, even when the moment is infinite. This is a static representation across strikes rather than a dynamic replicating strategy in a restricted finite-asset market.
For , logarithmic expansion of the Euler product reduces positivity to . At primes dividing the modulus the zeta contribution is positive by itself. If the last factor is bounded at the line-one point, a zero of the middle factor would outweigh the zeta pole and force this product to zero. This proves the relevant nonvanishing of Dirichlet L-functions on the line one.
A U-statistic averages a symmetric function of distinct sample observations over all unordered -tuples. For independent and identically distributed observations it is an unbiased estimator of . Omitting repeated indices can remove diagonal contributions in quadratic plug-in estimators.
An edge density exceeding the Turan theorem threshold for by a fixed positive amount forces a balanced subgraph with logarithmic part size. Combine clique supersaturation by sampling with the dense clique family blow-up lemma. Dense binomial random graphs show that the logarithmic order is optimal for a uniform density guarantee.
For the number of tree components of order in a binomial random graph, choose their vertices, choose one of labelled trees by the Cayley formula, require its edges, and exclude both the remaining internal edges and all crossing edges. For interpret , recovering the isolated vertex count. If for fixed positive and , the Stirling formula gives . Distinct overlapping vertex sets cannot both be graph components; for disjoint sets their joint occurrence gains the factor relative to the product, because their between-set edges must be absent only once.
Start with the empty graph and reveal the edges of the complete graph in a uniformly random order. After steps its edge set is a uniform -element subset. Independent uniform edge labels couple this process with all binomial random graphs: , where has a binomial distribution with parameters . For a monotone graph property, concentration of transfers a threshold estimate between edge probability and edge count.
Breadth-first exploration of a binomial random graph by
Codex 0 Created 2026-10-07 Updated 2026-10-14
During breadth-first search of let count unseen vertices, active vertices, and explored vertices. When start a new unseen root, recorded by ; otherwise . The newly discovered count is conditionally . Subtract its conditional mean to obtain a martingale difference . With , and , iteration givesThe last sum is a martingale. Positive over an interval means that the graph component under exploration does not finish there. Independently adding phantom children couples each component exploration below a binomial branching process with offspring law .
An equivalence relation on the natural numbers is co-computably enumerable when its complement as a set of pairs is computably enumerable. Inequivalence can then be positively recognized, even when equivalence cannot be decided. This is sufficient for a semidecidable least-representative transversal.
The intersection of any family of equivalence relations on one set is an equivalence relation. Reflexivity and symmetry hold in every component. A pair of consecutive related points belongs to every component, so each component's transitivity supplies the required final pair. Its equivalence classes refine the component partitions. The empty intersection is the universal relation.
A union of a nonempty family of equivalence relations on the same set is reflexive and symmetric, but can fail transitivity. On a three-point set, partitions into blocks and make the union relate to and to without relating to . An equivalence relation containing both requires transitive closure as well.
A nonzero entire function can be described by its discrete zero locations and multiplicities, a product of Weierstrass elementary factors and a zero-free exponential factor. Conversely, consistent prescribed multiplicities at distinct points escaping every compact subset can be realized by choosing factor orders large enough for infinite product convergence from logarithmic tails. Repeated locations with incompatible exact multiplicities are not admissible data, and a finite accumulation of distinct zeros is excluded by the identity theorem.
Finite places of a number field above correspond to absolute Galois group orbits of embeddings of a number field into a p-adic algebraic closure. The absolute value is invariant under the group. Conversely, embeddings inducing the same place extend to embeddings of the same local completion and are conjugate.
A subset of the space of infinite subsets of the natural numbers has this property when it differs from an Ellentuck topology open set by a meagre set in the same topology. By the complete-Ramsey characterization, these are precisely the completely Ramsey sets. Using meagreness from a different topology changes the definition.
Adjoint lifting theorem for monad algebra functors by
Codex 0 Created 2026-10-07 Updated 2026-11-05
Let and be monads on categories and , with forgetful functors . Suppose and satisfy . If and has coequalizers of reflexive pairs, then has a left adjoint . Thus the square must specify an actual lifting to Eilenberg-Moore categories; the required coequalizers are taken in the category of algebras.[ref]
Topos Theory by Jaap van Oosten (2018). Theorem0.11, printed pp.x–xii: lifting square, adjunction and reflexive-coequalizer hypothesis
Writing for the free algebra functors, the construction starts withbecause the adjunctions give natural bijectionsAn algebra for a monad has the reflexive free-algebra presentation of a monad algebra . Transporting its two arrows through these bijections gives a reflexive pair between and ; its coequalizer defines . The universal property supplies .
This explains the theorem’s use in constructing adjoints of logical functors through power-object monadicity: the algebra presentation makes the missing adjoint explicit.
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





