This article relies too much on references to primary sources .(July 2017) |

Type of business | Private |
---|---|

Type of site | Internet encyclopedia project |

Available in | English |

Owner | Wolfram Research, Inc. (for-profit) |

Created by | Eric W. Weisstein ^{ [1] } and other contributors |

URL | mathworld.wolfram.com |

Commercial | Yes |

Registration | Not required for viewing |

Launched | November 1999 (available at another location since 1995^{ [2] }) |

Current status | Active |

Content license | All rights reserved (copyright held by contributors and non-exclusively licensed to Wolfram Research, Inc., free for personal and educational use)^{ [3] }^{ [4] } |

* MathWorld* is an online mathematics reference work, created and largely written by Eric W. Weisstein. It is sponsored by and licensed to Wolfram Research, Inc. and was partially funded by the National Science Foundation's National Science Digital Library grant to the University of Illinois at Urbana–Champaign.

Eric W. Weisstein, the creator of the site, was a physics and astronomy student who got into the habit of writing notes on his mathematical readings. In 1995 he put his notes online and called it "Eric's Treasure Trove of Mathematics." It contained hundreds of pages/articles, covering a wide range of mathematical topics. The site became popular as an extensive single resource on mathematics on the web. Weisstein continuously improved the notes and accepted corrections and comments from online readers. In 1998, he made a contract with CRC Press and the contents of the site were published in print and CD-ROM form, titled "CRC Concise Encyclopedia of Mathematics." The free online version became only partially accessible to the public. In 1999 Weisstein went to work for Wolfram Research, Inc. (WRI), and WRI renamed the Math Treasure Trove to *MathWorld* and hosted it on the company's website^{ [5] } without access restrictions.

In 2000, CRC Press sued Wolfram Research Inc. (WRI), WRI president Stephen Wolfram, and author Eric Weisstein, due to what they considered a breach of contract: that the *MathWorld* content was to remain in print only. The site was taken down by a court injunction.^{ [6] }

The case was later settled out of court, with WRI paying an unspecified amount and complying with other stipulations. Among these stipulations is the inclusion of a copyright notice at the bottom of the website and broad rights for the CRC Press to produce *MathWorld* in printed book form. The site then became once again available free to the public.

This case made a wave of headlines in online publishing circles. The * PlanetMath * project was a result of MathWorld's being unavailable.^{ [7] }

In logic and related fields such as mathematics and philosophy, "**if and only if**" is a biconditional logical connective between statements, where either both statements are true or both are false.

In mathematics, and especially in category theory, a **commutative diagram** is a diagram such that all directed paths in the diagram with the same start and endpoints lead to the same result. It is said that commutative diagrams play the role in category theory that equations play in algebra.

**PlanetMath** is a free, collaborative, mathematics online encyclopedia. The emphasis is on rigour, openness, pedagogy, real-time content, interlinked content, and also community of about 24,000 people with various maths interests. Intended to be comprehensive, the project is currently hosted by the University of Waterloo. The site is owned by a US-based nonprofit corporation, "PlanetMath.org, Ltd".

In mathematics and logic, an **axiomatic system** is any set of axioms from which some or all axioms can be used in conjunction to logically derive theorems. A theory is a consistent, relatively-self-contained body of knowledge which usually contains an axiomatic system and all its derived theorems. An axiomatic system that is completely described is a special kind of formal system. A formal theory is an axiomatic system that describes a set of sentences that is closed under logical implication. A formal proof is a complete rendition of a mathematical proof within a formal system.

In mathematics, a **perfect magic cube** is a magic cube in which not only the columns, rows, pillars, and main space diagonals, but also the cross section diagonals sum up to the cube's magic constant.

**Wolfram Research, Inc.** is an American multinational company that creates computational technology. Wolfram's flagship product is the technical computing program Wolfram Mathematica, first released on June 23, 1988. Other products include WolframAlpha, Wolfram SystemModeler, Wolfram Workbench, gridMathematica, Wolfram Finance Platform, webMathematica, the Wolfram Cloud, and the Wolfram Programming Lab. Wolfram Research founder Stephen Wolfram is the CEO. The company is headquartered in Champaign, Illinois, United States.

**Eric Wolfgang Weisstein** is an encyclopedist who created and maintains *MathWorld* and *Eric Weisstein's World of Science* (*ScienceWorld*). He is the author of the *CRC Concise Encyclopedia of Mathematics*. He works for Wolfram Research, Inc.

In geometry, the **gyrobifastigium** is the 26th Johnson solid (*J*_{26}). It can be constructed by joining two face-regular triangular prisms along corresponding square faces, giving a quarter-turn to one prism. It is the only Johnson solid that can tile three-dimensional space.

In mathematics, the **boustrophedon transform** is a procedure which maps one sequence to another. The transformed sequence is computed by an "addition" operation, implemented as if filling a triangular array in a boustrophedon manner—as opposed to a "Raster Scan" sawtooth-like manner.

**Edgar van Tuyll** was the chief quantitative strategist of Pictet & Cie, where he worked from 1995 to 2017. He has been extensively quoted by the media for his prediction of the 2000 Dot-com bubble crash and of the bull market beginning in March 2003. He is among the minority of strategists expecting a US recession in 2007-2008. His website Links to unsolved problems, prizes and research is top ranked by Google for list of unsolved problems in mathematics and physics. He is the author of several entries in the "CRC Concise Encyclopedia of Mathematics", Chapman & Hall, 2002. He is the grandson of Antti Johannes Rantamaa.

In mathematics, an **operation** is a function which takes zero or more input values to a well-defined output value. The number of operands is the arity of the operation.

In geometry, a polytope of dimension 3 or higher is **isohedral** or **face-transitive** when all its faces are the same. More specifically, all faces must be not merely congruent but must be *transitive*, i.e. must lie within the same *symmetry orbit*. In other words, for any faces *A* and *B*, there must be a symmetry of the *entire* solid by rotations and reflections that maps *A* onto *B*. For this reason, convex isohedral polyhedra are the shapes that will make fair dice.

**Calculus** is a branch of mathematics focused on limits, functions, derivatives, integrals, and infinite series. This subject constitutes a major part of contemporary mathematics education. Calculus has widespread applications in science, economics, and engineering and can solve many problems for which algebra alone is insufficient.

In geometry, an **edge** is a particular type of line segment joining two vertices in a polygon, polyhedron, or higher-dimensional polytope. In a polygon, an edge is a line segment on the boundary, and is often called a **side**. In a polyhedron or more generally a polytope, an edge is a line segment where two faces meet. A segment joining two vertices while passing through the interior or exterior is not an edge but instead is called a diagonal.

**Heiko Harborth** is Professor of Mathematics at Braunschweig University of Technology, 1975–present, and author of more than 188 mathematical publications. His work is mostly in the areas of number theory, combinatorics and discrete geometry, including graph theory.

In geometry, **central lines** are certain special straight lines that lie in the plane of a triangle. The special property that distinguishes a straight line as a central line is manifested via the equation of the line in trilinear coordinates. This special property is related to the concept of triangle center also. The concept of a central line was introduced by Clark Kimberling in a paper published in 1994.

* CRC Concise Encyclopedia of Mathematics* is a bestselling book by American author Eric W. Weisstein.

In differential geometry, **Catalan's minimal surface** is a minimal surface originally studied by Eugène Charles Catalan in 1855.

- ↑ Eric Weisstein (2007). "Making MathWorld".
*Mathematica Journal*.**10**(3). Archived from the original on 2012-07-09. Retrieved 2010-08-22. - ↑ "What is the history of MathWorld?".
*MathWorld Q&A*. Wolfram Research, Inc. Retrieved 8 February 2011. - ↑ "Is the material on MathWorld copyrighted?".
*MathWorld Q&A*. Wolfram Research, Inc. Retrieved 8 February 2011. - ↑ W., Weisstein, Eric. "Terms of Use".
*mathworld.wolfram.com*. - ↑ W., Weisstein, Eric. "Wolfram MathWorld: The Web's Most Extensive Mathematics Resource".
*mathworld.wolfram.com*. - ↑
*The Value of a Good Idea: Protecting Intellectual Property in an Information Economy*. Silver Lake Publishing. 2002. p. 42. ISBN 9781563437458.mathworld copyright.

- ↑ Corneli, Joseph (2011). "The PlanetMath Encyclopedia" (PDF).
*ITP 2011 Workshop on Mathematical Wikis (MathWikis 2011) Nijmegen, Netherlands, August 27, 2011*.

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Images, videos and audio are available under their respective licenses.