set of sieves
1Subobject classifier — In category theory, a subobject classifier is a special object Omega; of a category; intuitively, the subobjects of an object X correspond to the morphisms from X to Omega;. As the name suggests, what a subobject classifier does is to… …
2Threshing machine — The thrashing machine, or, in modern spelling, threshing machine (or simply thresher), was a machine first invented by Scottish mechanical engineer Andrew Meikle for use in agriculture. It was invented (c.1784) for the separation of grain from… …
3Huller — A huller (or sometimes called a rice husker) is a kind of agricultural machinery to hull rice.To hull rice is to remove chaffs, the outer husks of the grain. There were many ways to hull rice in ancient times, but nowadays a huller, or rice… …
4Grothendieck topology — In category theory, a branch of mathematics, a Grothendieck topology is a structure on a category C which makes the objects of C act like the open sets of a topological space. A category together with a choice of Grothendieck topology is called a …
5Sieve (category theory) — In category theory, a branch of mathematics, a sieve is a way of choosing arrows with a common codomain. It is a categorical analogue of a collection of open subsets of a fixed open set in topology. In a Grothendieck topology, certain sieves… …
6Combine harvester — A Lely open cab combine. Harvesting oats in a C …
7petroleum refining — Introduction conversion of crude oil into useful products. History Distillation of kerosene and naphtha The refining of crude petroleum owes its origin to the successful drilling of the first oil well in Titusville, Pa., in 1859. Prior to… …
8Parity problem (sieve theory) — In number theory, the parity problem refers to a limitation in sieve theory that prevents sieves from giving good estimates in many kinds of prime counting problems. The problem was identified and named by Atle Selberg in 1949. Beginning around… …
9Lehmer sieve — Lehmer sieves are named for Derrick Norman Lehmer and his son Derrick Henry Lehmer. The father was a professor of mathematics at the University of California, Berkeley at the time, and his son was to follow in his footsteps, as a number theorist… …
10Sieve theory — is a set of general techniques in number theory, designed to count, or more realistically to estimate the size of, sifted sets of integers. The primordial example of a sifted set is the set of prime numbers up to some prescribed limit X .… …
