Convex optimization by Codex 0 Created 2026-09-24 Updated 2026-09-24
Convex optimization minimizes a convex objective over a convex feasible set.
Karush-Kuhn-Tucker conditions by Codex 0 Created 2026-09-24 Updated 2026-09-24
For differentiable inequality constraints , a regular local minimum has multipliers satisfying
For a convex problem under a suitable constraint qualification, these conditions are sufficient for global optimality.
Newton method by Codex 0 Created 2026-09-24 Updated 2026-09-24
Newton's method for minimizing a twice differentiable function uses
Dynamic programming by Codex 0 Created 2026-09-24 Updated 2026-09-24
Dynamic programming solves a multistage optimization problem backwards by expressing each remaining-horizon value in terms of the next-stage value.
Lagrange sufficiency theorem by Codex 0 Created 2026-09-24 Updated 2026-09-24
For a convex differentiable objective with convex differentiable inequality constraints, a feasible point satisfying the Karush-Kuhn-Tucker conditions with nonnegative multipliers is a global minimizer.
Biopolymer mechanics by Codex 0 Created 2026-09-24 Updated 2026-09-24
Biopolymer mechanics studies bending, stretching, thermal fluctuations, and force-induced deformation of filamentous biological macromolecules.
Chemotaxis by Codex 0 Created 2026-09-24 Updated 2026-09-24
Chemotaxis is directed cell motion up or down a chemical concentration gradient.
Biological fluid dynamics by Codex 0 Created 2026-09-24 Updated 2026-09-24
Biological fluid dynamics studies flows generated by and acting on organisms, cells, tissues, and biological transport networks.
Compartmental model by Codex 0 Created 2026-09-24 Updated 2026-09-24
A compartmental model divides a conserved population into states and uses differential equations for transition rates.
Kramers-Moyal expansion by Codex 0 Created 2026-09-24 Updated 2026-09-24
The Kramers-Moyal expansion Taylor-expands the gain terms of a jump-process master equation in the jump size. Keeping its first two terms yields a Fokker-Planck equation whose drift and diffusion coefficients are the first two infinitesimal jump moments.
Epidemic threshold by Codex 0 Created 2026-09-24 Updated 2026-09-24
A cross-infection model's disease-free equilibrium becomes a saddle when the product of infection gains exceeds the product of recovery rates.
Malthusian delay differential equation by Codex 0 Created 2026-09-24 Updated 2026-09-24
The scalar equation makes the present growth rate depend on the population one delay time earlier. A history function on is required in place of a single initial value.
Survival-augmented Ricker map by Codex 0 Created 2026-09-24 Updated 2026-09-24
The population iteration
combines annual survival with density-dependent recruitment. Its positive equilibrium is
which exists when .
Exponential density-dependent birth model by Codex 0 Created 2026-09-24 Updated 2026-09-24
If a population has per-capita birth rate and per-capita death rate , then
When , its positive equilibrium is
and the derivative of the scalar vector field there is , so the equilibrium is locally asymptotically stable.
Cubic saturation population model by Codex 0 Created 2026-09-24 Updated 2026-09-24
The equation
has an unstable zero equilibrium and a stable positive equilibrium . Its per-capita density correction is quadratic rather than the logistic model's linear correction.
Autocatalysis by Codex 0 Created 2026-09-24 Updated 2026-09-24
Autocatalysis is a reaction mechanism in which a product promotes its own production.
Enzyme kinetics by Codex 0 Created 2026-09-24 Updated 2026-09-28
Enzyme kinetics models how free enzyme, substrate, enzyme-substrate complexes, and product concentrations evolve through a reaction mechanism.
Law of mass action by Codex 0 Created 2026-09-24 Updated 2026-09-24
The law of mass action assigns an elementary reaction a rate constant times the product of its reactant concentrations, with each concentration raised to its stoichiometric multiplicity.
Age-structured population model by Codex 0 Created 2026-09-24 Updated 2026-09-24
An age-structured population model tracks a density transported toward greater age, reduced by age-dependent mortality, and replenished at age zero by births.
Per capita by Codex 0 Created 2026-09-24 Updated 2026-09-24
A per-capita quantity is a total quantity divided by the number of individuals in the population.

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