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  2. Deletion–contraction formula - Wikipedia

    en.wikipedia.org/wiki/Deletion–contraction_formula

    In graph theory, a deletion-contraction formula / recursion is any formula of the following recursive form: = + (/). Here G is a graph, f is a function on graphs, e is any edge of G, G \ e denotes edge deletion, and G / e denotes contraction. Tutte refers to such a function as a W-function. [1]

  3. Euler's identity - Wikipedia

    en.wikipedia.org/wiki/Euler's_identity

    The number e (e = 2.718...), also known as Euler's number, which occurs widely in mathematical analysis The number i , the imaginary unit such that i 2 = − 1 {\displaystyle i^{2}=-1} The equation is often given in the form of an expression set equal to zero, which is common practice in several areas of mathematics.

  4. e (mathematical constant) - Wikipedia

    en.wikipedia.org/wiki/E_(mathematical_constant)

    The number e is a mathematical constant approximately equal to 2.71828 that is the base of the natural logarithm and exponential function.It is sometimes called Euler's number, after the Swiss mathematician Leonhard Euler, though this can invite confusion with Euler numbers, or with Euler's constant, a different constant typically denoted .

  5. Reachability - Wikipedia

    en.wikipedia.org/wiki/Reachability

    In graph theory, reachability refers to the ability to get from one vertex to another within a graph. A vertex s {\displaystyle s} can reach a vertex t {\displaystyle t} (and t {\displaystyle t} is reachable from s {\displaystyle s} ) if there exists a sequence of adjacent vertices (i.e. a walk ) which starts with s {\displaystyle s} and ends ...

  6. Incidence matrix - Wikipedia

    en.wikipedia.org/wiki/Incidence_matrix

    In graph theory an undirected graph has two kinds of incidence matrices: unoriented and oriented. The unoriented incidence matrix (or simply incidence matrix ) of an undirected graph is a n × m {\displaystyle n\times m} matrix B , where n and m are the numbers of vertices and edges respectively, such that

  7. Cartesian product of graphs - Wikipedia

    en.wikipedia.org/wiki/Cartesian_product_of_graphs

    In graph theory, the Cartesian product G H of graphs G and H is a graph such that: the vertex set of G H is the Cartesian product V(G) × V(H); and; two vertices (u,v) and (u' ,v' ) are adjacent in G H if and only if either u = u' and v is adjacent to v' in H, or; v = v' and u is adjacent to u' in G.

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    mail.aol.com

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  9. Graph theory - Wikipedia

    en.wikipedia.org/wiki/Graph_theory

    Graph theory is also widely used in sociology as a way, for example, to measure actors' prestige or to explore rumor spreading, notably through the use of social network analysis software. Under the umbrella of social networks are many different types of graphs. [ 17 ]