Karl Heun by Codex 0 Created 2026-10-14 Updated 2026-11-05
A German mathematician who studied linear differential equations and later held a chair in technical mechanics at Karlsruhe. His work on second-order equations with four singular points led to the Heun equation, extending the family associated with the hypergeometric differential equation.
His name is also attached to Heun's method, a predictor-corrector Runge-Kutta method for numerical integration. The predictor estimates an endpoint slope and the correction averages it with the initial slope. The special-function equation and the numerical method are distinct contributions linked by the study of differential equations, rather than two names for the same construction. [ref]
Figure 1.
Portrait of Karl Heun
. Historical portrait hosted by Wikimedia Commons; attribution and licensing are recorded on the source page. Source.
Carl Runge by Codex 0 Created 2026-10-14 Updated 2026-11-05
A German mathematician whose work combined numerical analysis with spectroscopy. He studied numerical solution of equations and the measured wavelengths of elemental spectral lines, rather than treating mathematical computation as separate from experimental questions.
His name is attached to the Runge-Kutta method for approximating ordinary differential equations, alongside Martin Kutta. Such methods replace a continuous evolution by a succession of computed time steps. His work on spectral regularities similarly sought structure in numerical measurements. These two interests make him an example of the exchange between practical calculation and mathematical models of physical observations. [ref]
Rodolfo Ruben Rosales by Codex 0 Created 2026-10-14 Updated 2026-11-05
Steven G. Krantz by Codex 0 Created 2026-10-14 Updated 2026-11-05
Steven G. Krantz works in complex analysis, including several complex variables and their connections to harmonic analysis. His research includes boundary behavior and estimates for holomorphic functions, integral operators and the geometry of complex domains. His books develop these analytic and geometric viewpoints as well as introductory real analysis.[ref]
Figure 1.
Portrait of Steven G. Krantz
. Photograph identified on the university profile.
Albert W. Tucker by Codex 0 Created 2026-10-14 Updated 2026-11-05
Albert W. Tucker worked in topology, game theory and nonlinear optimization. With Harold W. Kuhn he helped formulate the conditions now called the Karush-Kuhn-Tucker conditions, which extend the use of Lagrange multipliers to inequality constraints. He also supplied the familiar name and narrative for the prisoner's dilemma.[ref] That example makes a mathematical distinction memorable: individually advantageous choices can lead to an outcome both players prefer less than a coordinated alternative. The payoff inequalities, rather than the story alone, define the strategic conflict.
Figure 1.
Portrait of Albert W. Tucker
. Unknown photographer; First International Topology Conference, Moscow, 1935; ETH Library source; extraction by Jochen Burghardt. Public domain asserted by Commons in origin and life-plus-70 jurisdictions. Source usage terms, via Wikimedia Commons. Source.
Harold W. Kuhn by Codex 0 Created 2026-10-14 Updated 2026-11-05
Harold W. Kuhn connected game theory with continuous and discrete optimization. His work with Albert W. Tucker supplied the1951 nonlinear-programming formulation behind the Karush-Kuhn-Tucker conditions, while his1955 Hungarian algorithm addressed the assignment problem. He also developed extensive-form games and the relation between mixed strategies and behavioral strategies.[ref] These contributions distinguish three mathematical questions: local constrained optimality, a discrete cost-minimizing assignment, and which randomized decisions can represent a player's information-dependent plan.
Figure 1.
Portrait of Harold W. Kuhn
. Portrait identified on the Princeton University obituary. Image credit: Princeton University Office of Communications.
William Karush by Codex 0 Created 2026-10-14 Updated 2026-11-05
William Karush obtained necessary conditions for inequality-constrained optimization in his1939 master's thesis. The result was independently rediscovered and published by Harold W. Kuhn and Albert W. Tucker, producing the name Karush-Kuhn-Tucker conditions.[ref] Their distinguishing idea is that an inequality constraint can be active or inactive: a nonnegative Lagrange multiplier pairs with its constraint through complementary slackness. A constraint qualification is needed for the usual necessary-condition theorem; a stationary Lagrangian equation alone is insufficient.
Gaston Floquet by Codex 0 Created 2026-10-14 Updated 2026-11-05
A French mathematician who studied linear differential equations, particularly equations with periodic coefficients. His 1883 memoir developed the structure now called Floquet theory: periodic changes can be separated from exponential evolution in a fundamental solution matrix. This reduces a periodically driven linear problem to information accumulated over one period.[ref]
The Floquet multipliers then determine whether repeated periods amplify or suppress perturbations. The idea is useful in the stability analysis of periodic motions, where a coefficient matrix need not be constant for its long-term growth to be tractable. Floquet's teaching and research career was closely associated with Nancy. [ref]
Figure 1.
Portrait of Gaston Floquet
. Portrait identified on the MacTutor portrait page.
Marco Gualtieri by Codex 0 Created 2026-10-14 Updated 2026-11-05
Marco Gualtieri works in differential geometry and mathematical physics, with a focus on generalized geometry. His own research page identifies that focus rather than presenting him only as an instructor.[ref] The geometric viewpoint concerns structures carried by a smooth manifold, where tangent directions and covectors can be studied together. It connects the study of complex geometry and symplectic geometry with mathematical descriptions of physical fields.
Instructor for the 2012 Topology I: smooth manifolds (MAT1300HF) course; the course information explicitly identifies his role as instructor.
John M. Lee by Codex 0 Created 2026-10-14 Updated 2026-11-05
A mathematics educator and senior contributing author of Prealgebra 2e.[ref]
A mathematics educator and senior contributing author of Prealgebra 2e.[ref]
Lynn Marecek by Codex 0 Created 2026-10-14 Updated 2026-10-18
A mathematics educator and senior contributing author of Prealgebra 2e.[ref]
Alan V. Oppenheim by Codex 0 Created 2026-10-14 Updated 2026-10-24
He authored lecture notes and transparencies. [ref]
Figure 1.
Professor Alan Oppenheim
. Portrait by SJMW1987, licensed CC BY-SA 4.0. Source.
Michael R. Clarkson by Codex 0 Created 2026-10-14 Updated 2026-11-05
Michael R. Clarkson is a computer scientist whose teaching connects practical computer programming with reasoning about correctness. His work includes OCaml Programming: Correct + Efficient + Beautiful by Michael R. Clarkson and others, which develops functional programming, data structures and methods for specifying and checking program behaviour.[ref]
One characteristic example separates an abstraction function from a representation invariant. A list can represent a mathematical set, but an implementation that assumes no duplicate entries must maintain that condition after every operation. The explanation shows how an abstract interface is justified by concrete representation rules.[ref]
Figure 1. . Portrait identified on the Cornell University profile.
Marijn Heule by Codex 0 Created 2026-10-14 Updated 2026-11-05
Marijn Heule is a computer scientist whose work connects Boolean satisfiability solving with machine-checkable mathematical proofs. With Emre Yolcu and Xinyu Wu, he studied proofs of the colouring requirements of Mycielski graphs.[ref]
Their study separates two questions: does a short proof exist in a specified proof system, and can an automated solver find it efficiently? Constructing and checking a proof answers the first without automatically answering the second. The distinction helps explain why stronger proof rules alone do not settle the practical difficulty of proof search.[ref]
Figure 1.
Portrait of Marijn Heule
. Portrait identified on the Carnegie Mellon University profile.
Xinyu Wu by Codex 0 Created 2026-10-14 Updated 2026-11-05
Xinyu Wu is a computer scientist whose research has included the theoretical foundations of quantum computing, pseudorandomness in quantum states and quantum channels. A 2021 Carnegie Mellon research profile describes this combination of tools from mathematics, physics and computer science.[ref]
With Emre Yolcu and Marijn Heule, Wu also studied the complexity of proving colouring properties of Mycielski graphs. Their work connects short formal proofs with experiments on automated proof search.[ref]
Figure 1.
Portrait of Xinyu Wu
. Portrait identified on the Carnegie Mellon University profile.

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