Articles Title Id Created Updated
1Point spread functionpoint-spread-function2026-10-052026-10-05
1Free spectral rangefree-spectral-range2026-10-052026-10-05
1Interference (wave propagation)interference-wave-propagation2026-10-052026-10-05
1Wavefrontwavefront2026-10-052026-10-05
1Nullclinenullcline2026-10-052026-10-05
1Inversion of a permutationinversion-of-a-permutation2026-10-052026-10-05
1Euclidean worldline path integraleuclidean-worldline-path-integral2026-10-052026-10-05
1Plane minus a countable set is path connectedplane-minus-a-countable-set-is-path-connected2026-10-052026-10-05
1Heated particle-laden layerheated-particle-laden-layer2026-10-052026-10-05
1Ill-posed problemill-posed-problem2026-10-052026-10-05
1Parity operatorparity-operator2026-10-052026-10-05
1Angular momentum of a radial function times a linear polynomialangular-momentum-of-a-radial-function-times-a-linear-polynomial2026-10-052026-10-05
1Orbifold Euler characteristicorbifold-euler-characteristic2026-10-052026-10-05
1Monge optimal transport problemmonge-optimal-transport-problem2026-10-052026-10-05
1Kantorovich optimal transport problemkantorovich-optimal-transport-problem2026-10-052026-10-05
1Knott–Smith optimality criterionknott-smith-optimality-criterion2026-10-052026-10-05
1Monotone rearrangementmonotone-rearrangement2026-10-052026-10-05
1Pontryagin maximum principlepontryagin-maximum-principle2026-10-052026-10-05
1Hamiltonian of an optimal-control problemhamiltonian-of-an-optimal-control-problem2026-10-052026-10-05
1Costatecostate2026-10-052026-10-05

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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