Planar separator theorem
The Planar Separator Theorem is a concept in computational geometry and graph theory which states that for any planar graph, it is possible to partition the vertices of the graph into three disjoint sets: X, Y, and S. The sets have the following properties: 1. **Small Separator Size**: The size of the set S (the separator) is proportional to the square root of the number of vertices in the graph.
Strong perfect graph theorem
The Strong Perfect Graph Theorem, proved by Maria Chudnovsky, Neil Robertson, Paul Seymour, and Robin Thomas in 2006, establishes an important characterization of perfect graphs. The theorem states that a graph is perfect if and only if it contains no induced subgraph that is an odd cycle of length at least 5 or the complement of such a cycle (i.e., a complete graph minus an odd cycle).
Veblen's theorem
Veblen's theorem is a result in the field of set theory and topology, specifically in the context of the study of properties of certain sets. It primarily deals with the concept of "well-ordering." The theorem states that every set can be well-ordered, meaning that its elements can be arranged in a sequence such that every non-empty subset has a least element.
Schur's theorem
Schur's theorem is a result in the field of combinatorics and number theory, and it is often associated with Ramsey theory.
Helmholtz's theorems
Helmholtz's theorems, named after the German physicist Hermann von Helmholtz, are fundamental results in the fields of fluid dynamics and vector calculus, particularly concerning the representation of vector fields.
Midpoint theorem (conics)
The Midpoint Theorem in the context of conics, specifically concerning ellipses, refers to a property related to the midpoints of line segments connecting points on the ellipse. While the term "Midpoint Theorem" can also be associated with other geometrical contexts, such as triangles, in the realm of conics, it is often used to describe certain relationships and properties referring to the midpoints of chords.
Cayley–Bacharach theorem
The Cayley–Bacharach theorem is a result in algebraic geometry that deals with the intersection of divisors on a projective space. It is particularly relevant in the study of linear systems of divisors and their properties. In its classical form, the theorem states the following: Let \( C \) be a non-singular irreducible curve of degree \( d \) in the projective plane \( \mathbb{P}^2 \).
Quantum chemistry
Quantum chemistry is a branch of chemistry that applies the principles of quantum mechanics to study the behavior of atoms and molecules. It seeks to understand how quantum effects influence chemical properties and reactions. Here are some key aspects of quantum chemistry: 1. **Wave-Particle Duality**: Quantum chemistry leverages the concept that particles, such as electrons, exhibit both wave-like and particle-like properties, which is fundamental in explaining their behavior in atomic and molecular systems.
Weather
Weather refers to the atmospheric conditions in a specific place over a short period of time, typically hours to days. It encompasses various elements, including temperature, humidity, precipitation (such as rain or snow), wind speed and direction, atmospheric pressure, and cloud cover. Weather can change rapidly and is influenced by several factors, including geographic location, time of year, and local atmospheric conditions.
Edge-of-the-wedge theorem
The Edge-of-the-Wedge theorem is a concept from complex analysis, specifically regarding holomorphic functions. It deals with the behavior of these functions on regions in the complex plane that have "wedge-shaped" domains.
Theorems about circles
Circles are fundamental shapes in geometry, and several important theorems govern their properties and behaviors. Here are some key theorems about circles: 1. **Circumference Theorem**: The circumference \( C \) of a circle is given by the formula: \[ C = 2\pi r \] where \( r \) is the radius of the circle.
Theorems about polygons
Theorems about polygons constitute a significant part of geometry, focusing on the properties, relationships, and characteristics of various types of polygons.
Hjelmslev's theorem
Hjelmslev's theorem is a result in the field of projective geometry that relates to the properties of conics (i.e., curves defined by quadratic equations) in projective spaces. Specifically, it addresses the conditions under which a conic in one projective plane can be transformed into an equivalent conic in another projective plane.
Alan Turing
Alan Turing was a British mathematician, logician, cryptanalyst, and computer scientist, widely regarded as one of the fathers of computer science and artificial intelligence. Born on June 23, 1912, Turing made significant contributions to various fields, including mathematics, logic, and computer science. One of his most notable accomplishments during World War II was his work at Bletchley Park, where he played a crucial role in breaking the German Enigma code.
Charles Darwin
Charles Darwin was a British naturalist, geologist, and biologist best known for his contributions to the understanding of evolution. Born on February 12, 1809, he is most famous for developing the theory of natural selection, which explains how species evolve over time through the process of heritable variation and survival of the fittest.
Claus Emmeche
Claus Emmeche is a Danish biologist known for his work in various fields, including philosophy of biology, cognitive science, and the study of complex systems. He has contributed to discussions about the nature of life, the relationship between biology and philosophy, and the implications of biological research for understanding consciousness and cognition. Emmeche has published several scholarly articles and has been involved in interdisciplinary research projects that bridge the gap between science and philosophy.
Ali Alavi
Ali Alavi could refer to multiple individuals, but without specific context, it's difficult to pinpoint exactly which Ali Alavi you are referring to. He could be an academic, a professional in a certain field, or someone notable in a particular area such as business, arts, or sports.
Ferromagnetism
Ferromagnetism is a fundamental magnetic property of certain materials, primarily metals, characterized by a strong attraction to magnetic fields and the ability to retain magnetization even after the external magnetic field is removed. This behavior is due to the alignment of magnetic moments of atomic or molecular dipoles within the material.