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In graph theory, ΔY- and YΔ-transformations (also written delta-wye and wye-delta) are a pair of operations on graphs. A ΔY-transformation replaces a triangle by a vertex of degree three; and conversely, a YΔ-transformation replaces a vertex of degree three by a triangle. The names for the operations derive from the shapes of the involved ...
This circuit transformation theory was published by Arthur Edwin Kennelly in 1899. [1] It is widely used in analysis of three-phase electric power circuits. The Y-Δ transform can be considered a special case of the star-mesh transform for three resistors. In mathematics, the Y-Δ transform plays an important role in theory of circular planar ...
In mathematics, graph theory is the study of graphs, which are mathematical structures used to model pairwise relations between objects. A graph in this context is made up of vertices (also called nodes or points) which are connected by edges (also called arcs, links or lines).
ΔY- and YΔ-transformation of a polyhedron. Although Steinitz's original proof was not expressed in terms of graph theory, it can be rewritten in those terms, and involves finding a sequence of ΔY- and YΔ-transformations that reduce any 3-connected planar graph to , the graph of the tetrahedron. A YΔ-transformation removes a degree-three ...
In graph theory, the Petersen family is a set of seven undirected graphs that includes the Petersen graph and the complete graph K6. The Petersen family is named after Danish mathematician Julius Petersen, the namesake of the Petersen graph. Any of the graphs in the Petersen family can be transformed into any other graph in the family by YΔ ...
Graph rewriting. In computer science, graph transformation, or graph rewriting, concerns the technique of creating a new graph out of an original graph algorithmically. It has numerous applications, ranging from software engineering (software construction and also software verification) to layout algorithms and picture generation.
The defining properties of any LTI system are linearity and time invariance.. Linearity means that the relationship between the input () and the output (), both being regarded as functions, is a linear mapping: If is a constant then the system output to () is (); if ′ is a further input with system output ′ then the output of the system to () + ′ is () + ′ (), this applying for all ...
A schematic diagram of the Blasius flow profile. The streamwise velocity component () / is shown, as a function of the similarity variable .. Using scaling arguments, Ludwig Prandtl [1] argued that about half of the terms in the Navier-Stokes equations are negligible in boundary layer flows (except in a small region near the leading edge of the plate).