Definitionen
1.Nouncoproduct in some categories, like abelian groups, topological spaces or modules
2.NounA linear sum in which the intersection of the summands has dimension zero. Equivalently, a linear sum of two subspaces, any vector of which can be expressed uniquely as a sum of two vectors: one vector belonging to the first subspace, and the other vector belonging to the second subspace.
3.NounA block diagonal matrix interpreted as having its non-zero blocks (which are square matrices) as summands.
4.Noun↑ Garrett Birkhoff with Saunders Mac Lane (©1953), A Survey Of Modern Algebra, Revised edition, U.S.A.: The Macmillan Company, published 1960 (9th printing), §X.8, page 326
5.Noun↑ David Steven Dummit with Richard M. Foote (©2004), Abstract Algebra, third edition, U.S.A.: John Wiley & Sons, Inc., →ISBN, →OCLC, §12.2, page 475
6.Noun↑ Kenneth Myron Hoffman with Ray Alden Kunze (©1971), Linear Algebra, second edition, Upper Saddle River, New Jersey: Prentice-Hall, Inc., →ISBN, →OCLC, §6.7, page 214