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In graph theory, a branch of combinatorial mathematics, a block graph or clique tree [1] is a type of undirected graph in which every biconnected component (block) is a clique. Block graphs are sometimes erroneously called Husimi trees (after Kôdi Husimi ), [ 2 ] but that name more properly refers to cactus graphs , graphs in which every ...
Pratt based her blocks on a similar but larger-scale block system designed by educator Patty Hill, a follower of Friedrich Fröbel, the originator of kindergarten education. Fröbel's series of 20 age-calibrated educational "gifts" had included a set of eight blocks, sized ½ by 1 by 2 inches, or a 1:2:4 ratio, which could be formed into a cube ...
The following scores (in addition to 1, 2, and 4) cannot be made from multiples of 5 and 7 and so are almost never seen in sevens: 3, 6, 8, 9, 11, 13, 16, 18 and 23. By way of example, none of these scores was recorded in any game in the 2014-15 Sevens World Series .
A simplex graph is an undirected graph κ(G) with a vertex for every clique in a graph G and an edge connecting two cliques that differ by a single vertex. It is an example of median graph , and is associated with a median algebra on the cliques of a graph: the median m ( A , B , C ) of three cliques A , B , and C is the clique whose vertices ...
The Bruhat–Tits tree for the 2-adic Lie group SL(2,Q 2). The notion of a building was invented by Jacques Tits as a means of describing simple algebraic groups over an arbitrary field. Tits demonstrated how to every such group G one can associate a simplicial complex Δ = Δ(G) with an action of G, called the spherical building of G.
The block graph of a given graph G is the intersection graph of its blocks. Thus, it has one vertex for each block of G, and an edge between two vertices whenever the corresponding two blocks share a vertex. A graph H is the block graph of another graph G exactly when all the blocks of H are complete subgraphs.
Every edge of a graph belongs in exactly one block. 2. The block graph of a graph G is another graph whose vertices are the blocks of G, with an edge connecting two vertices when the corresponding blocks share an articulation point; that is, it is the intersection graph of the blocks of G. The block graph of any graph is a forest. 3.
Two sets of "Fractional Pattern Blocks" exist: both with two blocks. [7] The first has a pink double hexagon and a black chevron equivalent to four triangles. The second has a brown half-trapezoid and a pink half-triangle. Another set, Deci-Blocks, is made up of six shapes, equivalent to four, five, seven, eight, nine and ten triangles ...