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In graph theory, a quotient graph Q of a graph G is a graph whose vertices are blocks of a partition of the vertices of G and where block B is adjacent to block C if ...
In geometric group theory, a graph of groups is an object consisting of a collection of groups indexed by the vertices and edges of a graph, together with a family of monomorphisms of the edge groups into the vertex groups. There is a unique group, called the fundamental group, canonically associated to each finite connected graph of
The quotient graph can be formed by deleting i from the tree, forming subsets of vertices in G corresponding to the leaves in each of the resulting subtrees, and collapsing each of these vertex sets into a single vertex. Every quotient graph has one of three forms: it may be a prime graph, a complete graph, or a star. [2]
The theory of tree lattices was developed by Bass, Kulkarni and Lubotzky [25] [26] by analogy with the theory of lattices in Lie groups (that is discrete subgroups of Lie groups of finite co-volume). For a discrete subgroup G of the automorphism group of a locally finite tree X one can define a natural notion of volume for the quotient graph of ...
for all g and h in G and all x in X.. The group G is then said to act on X (from the left). A set X together with an action of G is called a (left) G-set.. It can be notationally convenient to curry the action α, so that, instead, one has a collection of transformations α g : X → X, with one transformation α g for each group element g ∈ G.
A presentation of a group determines a geometry, in the sense of geometric group theory: one has the Cayley graph, which has a metric, called the word metric. These are also two resulting orders, the weak order and the Bruhat order, and corresponding Hasse diagrams. An important example is in the Coxeter groups.
The notion is a generalization of concepts such as subsets from set theory, subgroups from group theory, [1] and subspaces from topology. Since the detailed structure of objects is immaterial in category theory, the definition of subobject relies on a morphism that describes how one object sits inside another, rather than relying on the use of ...
3. In the theory of splits, cuts whose cut-set is a complete bipartite graph, a prime graph is a graph without any splits. Every quotient graph of a maximal decomposition by splits is a prime graph, a star, or a complete graph. 4. A prime graph for the Cartesian product of graphs is a connected graph that is not itself a product. Every ...