群组
· Group(群组):该命令可以将所选择的多个物体或组结合成一个组,并在场景中像单个物体一样编辑它。
[数 生物] 群
...积间断面(假整合和角度不整合)。组的符号,采用在系或统的后边加汉语拼音头一个字母,用小写斜体字表示、透镜体等。群(Group):$地层岩性划分地层。 什么是地层的划分和对比?
团体
团队(Team)和团体(Group)是不同的概念,两者的区别在于:团队是集体共同承担领导责任,团体只有一个能力突出的领导人;团队追求大于所有个人业绩之和的共...
成组
... treatment group治疗组;试验组 in group成组;成群 interest group利益集团(指有共同利益的一群人) ...
黑石集团 ; 黑石团体 ; 百仕通
塔塔集团 ; 印度塔塔集团 ; 塔塔团体 ; 达达集团
澳洲八校联盟 ; 八大名校 ; 八校联盟 ; 八国集团
In mathematics, a group is a set of elements together with an operation that combines any two of its elements to form a third element satisfying four conditions called the group axioms, namely closure, associativity, identity and invertibility. One of the most familiar examples of a group is the set of integers together with the addition operation; the addition of any two integers forms another integer. The abstract formalization of the group axioms, detached as it is from the concrete nature of any particular group and its operation, allows entities with highly diverse mathematical origins in abstract algebra and beyond to be handled in a flexible way, while retaining their essential structural aspects. The ubiquity of groups in numerous areas within and outside mathematics makes them a central organizing principle of contemporary mathematics.Groups share a fundamental kinship with the notion of symmetry. For example, a symmetry group encodes symmetry features of a geometrical object: the group consists of the set of transformations that leave the object unchanged and the operation of combining two such transformations by performing one after the other. Lie groups are the symmetry groups used in the Standard Model of particle physics; Point groups are used to help understand symmetry phenomena in molecular chemistry; and Poincaré groups can express the physical symmetry underlying special relativity.The concept of a group arose from the study of polynomial equations, starting with Évariste Galois in the 1830s. After contributions from other fields such as number theory and geometry, the group notion was generalized and firmly established around 1870. Modern group theory—an active mathematical discipline—studies groups in their own right.a[›] To explore groups, mathematicians have devised various notions to break groups into smaller, better-understandable pieces, such as subgroups, quotient groups and simple groups. In addition to their abstract properties, group theorists also study the different ways in which a group can be expressed concretely (its group representations), both from a theoretical and a computational point of view. A theory has been developed for finite groups, which culminated with the classification of finite simple groups announced in 1983.aa[›] Since the mid-1980s, geometric group theory, which studies finitely generated groups as geometric objects, has become a particularly active area in group theory.