Convex setIn geometry, a subset of a Euclidean space, or more generally an affine space over the reals, is convex if, given any two points in the subset, the subset contains the whole line segment that joins them. Equivalently, a convex set or a convex region is a subset that intersects every line into a single line segment (possibly empty). For example, a solid cube is a convex set, but anything that is hollow or has an indent, for example, a crescent shape, is not convex. The boundary of a convex set is always a convex curve.
Convex polygonIn geometry, a convex polygon is a polygon that is the boundary of a convex set. This means that the line segment between two points of the polygon is contained in the union of the interior and the boundary of the polygon. In particular, it is a simple polygon (not self-intersecting). Equivalently, a polygon is convex if every line that does not contain any edge intersects the polygon in at most two points. A strictly convex polygon is a convex polygon such that no line contains two of its edges.
ShapeA shape or figure is a graphical representation of an object or its external boundary, outline, or external surface, as opposed to other properties such as color, texture, or material type. A plane shape or plane figure is constrained to lie on a plane, in contrast to solid 3D shapes. A two-dimensional shape or two-dimensional figure (also: 2D shape or 2D figure) may lie on a more general curved surface (a non-Euclidean two-dimensional space). Lists of shapes Some simple shapes can be put into broad categories.
Convex geometryIn mathematics, convex geometry is the branch of geometry studying convex sets, mainly in Euclidean space. Convex sets occur naturally in many areas: computational geometry, convex analysis, discrete geometry, functional analysis, geometry of numbers, integral geometry, linear programming, probability theory, game theory, etc. According to the Mathematics Subject Classification MSC2010, the mathematical discipline Convex and Discrete Geometry includes three major branches: general convexity polytopes and polyhedra discrete geometry (though only portions of the latter two are included in convex geometry).
Carathéodory's theorem (convex hull)Carathéodory's theorem is a theorem in convex geometry. It states that if a point lies in the convex hull of a set , then can be written as the convex combination of at most points in . More sharply, can be written as the convex combination of at most extremal points in , as non-extremal points can be removed from without changing the membership of in the convex hull. Its equivalent theorem for conical combinations states that if a point lies in the conical hull of a set , then can be written as the conical combination of at most points in .
TheoremIn mathematics, a theorem is a statement that has been proved, or can be proved. The proof of a theorem is a logical argument that uses the inference rules of a deductive system to establish that the theorem is a logical consequence of the axioms and previously proved theorems. In mainstream mathematics, the axioms and the inference rules are commonly left implicit, and, in this case, they are almost always those of Zermelo–Fraenkel set theory with the axiom of choice (ZFC), or of a less powerful theory, such as Peano arithmetic.
Minkowski additionIn geometry, the Minkowski sum of two sets of position vectors A and B in Euclidean space is formed by adding each vector in A to each vector in B: The Minkowski difference (also Minkowski subtraction, Minkowski decomposition, or geometric difference) is the corresponding inverse, where produces a set that could be summed with B to recover A. This is defined as the complement of the Minkowski sum of the complement of A with the reflection of B about the origin. This definition allows a symmetrical relationship between the Minkowski sum and difference.
Curve of constant widthIn geometry, a curve of constant width is a simple closed curve in the plane whose width (the distance between parallel supporting lines) is the same in all directions. The shape bounded by a curve of constant width is a body of constant width or an orbiform, the name given to these shapes by Leonhard Euler. Standard examples are the circle and the Reuleaux triangle. These curves can also be constructed using circular arcs centered at crossings of an arrangement of lines, as the involutes of certain curves, or by intersecting circles centered on a partial curve.
Gödel's incompleteness theoremsGödel's incompleteness theorems are two theorems of mathematical logic that are concerned with the limits of in formal axiomatic theories. These results, published by Kurt Gödel in 1931, are important both in mathematical logic and in the philosophy of mathematics. The theorems are widely, but not universally, interpreted as showing that Hilbert's program to find a complete and consistent set of axioms for all mathematics is impossible. The first incompleteness theorem states that no consistent system of axioms whose theorems can be listed by an effective procedure (i.
Platonic solidIn geometry, a Platonic solid is a convex, regular polyhedron in three-dimensional Euclidean space. Being a regular polyhedron means that the faces are congruent (identical in shape and size) regular polygons (all angles congruent and all edges congruent), and the same number of faces meet at each vertex. There are only five such polyhedra: Geometers have studied the Platonic solids for thousands of years. They are named for the ancient Greek philosopher Plato who hypothesized in one of his dialogues, the Timaeus, that the classical elements were made of these regular solids.
Geometric measure theoryIn mathematics, geometric measure theory (GMT) is the study of geometric properties of sets (typically in Euclidean space) through measure theory. It allows mathematicians to extend tools from differential geometry to a much larger class of surfaces that are not necessarily smooth. Geometric measure theory was born out of the desire to solve Plateau's problem (named after Joseph Plateau) which asks if for every smooth closed curve in there exists a surface of least area among all surfaces whose boundary equals the given curve.
Isoperimetric inequalityIn mathematics, the isoperimetric inequality is a geometric inequality involving the perimeter of a set and its volume. In -dimensional space the inequality lower bounds the surface area or perimeter of a set by its volume , where is a unit sphere. The equality holds only when is a sphere in . On a plane, i.e. when , the isoperimetric inequality relates the square of the circumference of a closed curve and the area of a plane region it encloses. Isoperimetric literally means "having the same perimeter".
Kurt GödelKurt Friedrich Gödel (ˈɡɜːrdəl , kʊʁt ˈɡøːdl̩; April 28, 1906 – January 14, 1978) was a logician, mathematician, and philosopher. Considered along with Aristotle and Gottlob Frege to be one of the most significant logicians in history, Gödel had an immense effect upon scientific and philosophical thinking in the 20th century, a time when others such as Bertrand Russell, Alfred North Whitehead, and David Hilbert were using logic and set theory to investigate the foundations of mathematics, building on earlier work by the likes of Richard Dedekind, Georg Cantor and Frege.
Philippe de VilmorinJoseph-Marie-Philippe Lévêque de Vilmorin (21 May 1872 – 29 June 1917), generally known as Philippe de Vilmorin, was a noted French botanist and plant collector, and a member of the celebrated Vilmorin family of horticulturists. In 1903 Vilmorin began the Arboretum de Pézanin, an arboretum located in Dompierre-les-Ormes, Saône-et-Loire, Bourgogne, France. He also collected plants in Egypt and Sudan that now form part of the herbarium of the National Botanic Garden of Belgium.
VilmorinVilmorin is a French seed producer. The company has a long history in France, where it was family-controlled for almost two centuries, and today exists as a publicly traded company owned principally by agro-industrial cooperative Groupe Limagrain, the largest plant breeding and seed company in the European Union. Vilmorin was founded as a plant and seed boutique in 1743 by seed expert Claude Geoffroy and her husband Pierre Andrieux, the chief seed supplier and botanist to King Louis XV.
Mapie de Toulouse-LautrecMarie Pierre "Mapie" de Toulouse-Lautrec (1901–1972) was a French journalist and food writer, born Marie Pierre Adélaïde Lévêque de Vilmorin in Verrières-le-Buisson, scion of the Vilmorin seed company. Her horticulturalist father was Joseph Marie Philippe Lévêque de Vilmorin (1872-1917), and her mother was the former Bertha Marie Mélanie de Gaufridy de Dortan (1876-1937). The writer Louise de Vilmorin (1902–1969) was her younger sister, while one of her younger brothers, Roger, was the result of an affair between her mother and Alfonso XIII of Spain.
Crédit LyonnaisThe Crédit Lyonnais (kʁedi ljɔnɛ, "Lyon Credit [Company]") was a major French bank, created in 1863 and absorbed by former rival Crédit Agricole in 2003. Its head office was initially in Lyon but moved to Paris in 1882. In the early years of the 20th century, it was the world's largest bank by total assets. Its former French retail network survives as LCL S.A., a fully owned subsidiary of Crédit Agricole, under the brand LCL adopted in 2005 with reference to "Le Crédit Lyonnais".
French School at AthensThe French School at Athens (École française d’Athènes, EfA; Γαλλική Σχολή Αθηνών Gallikí Scholí Athinón) is one of the seventeen foreign archaeological institutes operating in Athens, Greece. Founded in 1846, the EfA is the oldest foreign institute in Athens. Its early foundation, still a source of considerable prestige, is to be seen culturally connected with French philhellenism and politically with the French East Mediterranean strategy of the time.
1920 in FranceEvents from the year 1920 in France. President: until 18 February: Raymond Poincaré 18 February – 21 September: Paul Deschanel starting 21 September: Alexandre Millerand President of the Council of Ministers: until 20 January: Georges Clemenceau 20 January – 24 September: Alexandre Millerand starting 24 September: Georges Leygues In the opening of the year 1920, France was in a stronger position than she had been in for several generations.
