Arithmetic combinatoricsIn mathematics, arithmetic combinatorics is a field in the intersection of number theory, combinatorics, ergodic theory and harmonic analysis. Arithmetic combinatorics is about combinatorial estimates associated with arithmetic operations (addition, subtraction, multiplication, and division). Additive combinatorics is the special case when only the operations of addition and subtraction are involved. Ben Green explains arithmetic combinatorics in his review of "Additive Combinatorics" by Tao and Vu.
Lagrangian systemIn mathematics, a Lagrangian system is a pair (Y, L), consisting of a smooth fiber bundle Y → X and a Lagrangian density L, which yields the Euler–Lagrange differential operator acting on sections of Y → X. In classical mechanics, many dynamical systems are Lagrangian systems. The configuration space of such a Lagrangian system is a fiber bundle Q → R over the time axis R. In particular, Q = R × M if a reference frame is fixed. In classical field theory, all field systems are the Lagrangian ones.
Hermann MinkowskiHermann Minkowski, né à Alexotas (alors en Russie, dans le Gouvernement de Suwałki, et aujourd'hui en Lituanie) le et mort à Göttingen le , est un mathématicien et un physicien théoricien allemand. Hermann Minkowski naît le à Alexotas près de Kaunas dans une famille juive. Il est le cadet des trois enfants de Lewin Minkowski et de son épouse Rachel, née Raubmann. En , les Minkowski quittent Alexotas pour Königsberg. Minkowski y passe le reste de son enfance.
Ben Joseph GreenBen Joseph Green (né le à Bristol en Angleterre) est un mathématicien de nationalité britannique spécialisé en combinatoire et en théorie des nombres. Il est connu pour avoir démontré le théorème de Green-Tao en collaboration avec le mathématicien Terence Tao. En 2004 il reçoit le Clay Research Award. Il reçoit le prix Salem, le Prix Whitehead et le Prix Ostrowski en 2005. En 2007 il est lauréat du prix SASTRA Ramanujan. En 2008, il reçoit le Prix de la Société mathématique européenne.
Conserved currentIn physics a conserved current is a current, , that satisfies the continuity equation . The continuity equation represents a conservation law, hence the name. Indeed, integrating the continuity equation over a volume , large enough to have no net currents through its surface, leads to the conservation law where is the conserved quantity. In gauge theories the gauge fields couple to conserved currents. For example, the electromagnetic field couples to the conserved electric current.
Hyperbolic orthogonalityIn geometry, the relation of hyperbolic orthogonality between two lines separated by the asymptotes of a hyperbola is a concept used in special relativity to define simultaneous events. Two events will be simultaneous when they are on a line hyperbolically orthogonal to a particular time line. This dependence on a certain time line is determined by velocity, and is the basis for the relativity of simultaneity. Two lines are hyperbolic orthogonal when they are reflections of each other over the asymptote of a given hyperbola.
