countable covering
21Locally finite collection — In the mathematical field of topology, local finiteness is a property of collections of subsets of a topological space. It is fundamental in the study of paracompactness and topological dimension. A collection of subsets of a topological space X… …
22Packing dimension — In mathematics, the packing dimension is one of a number of concepts that can be used to define the dimension of a subset of a metric space. Packing dimension is in some sense dual to Hausdorff dimension, since packing dimension is constructed by …
23ground — I UK [ɡraʊnd] / US noun Word forms ground : singular ground plural grounds *** 1) [singular/uncountable] the top part of the Earth s surface that people walk on I fell to the ground. on the ground: People were sitting on the ground in small… …
24letter — let‧ter [ˈletə ǁ ər] noun [countable] 1. a written or printed message that is usually put in an envelope and sent by mail: • Please sign the letter and mail it back within two weeks. alloˈcation ˌletter also alˈlotment ˌletter FINANCE a letter… …
25ice sheet — noun : a glacial ice cover : ice cap the ice sheets on some Greenland promontories especially : one (as a continental glacier) spreading outward over a large land area and concealing all or most surface features the great ice sheets covering much …
26Differentiable manifold — A nondifferentiable atlas of charts for the globe. The results of calculus may not be compatible between charts if the atlas is not differentiable. In the middle chart the Tropic of Cancer is a smooth curve, whereas in the first it has a sharp… …
27probability theory — Math., Statistics. the theory of analyzing and making statements concerning the probability of the occurrence of uncertain events. Cf. probability (def. 4). [1830 40] * * * Branch of mathematics that deals with analysis of random events.… …
28delivery — The transfer of the cash commodity from the seller of a futures contract to the buyer of a futures contract. Each futures exchange has specific procedures for delivery of a cash commodity. Some futures contracts, such as stock index contracts,… …
29Rotation matrix — In linear algebra, a rotation matrix is a matrix that is used to perform a rotation in Euclidean space. For example the matrix rotates points in the xy Cartesian plane counterclockwise through an angle θ about the origin of the Cartesian… …
30Metacompact space — In mathematics, in the field of general topology, a topological space is said to be metacompact if every open cover has a point finite open refinement. That is, given any open cover of the topological space, there is a refinement which is again… …
