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compU -- key in hash table gaussianRingData: component of undirected edges in vertex set of a mixed graph

Description

This key is present in every gaussianRingData that comes from a graph of class MixedGraph. It is equal to the set of vertices that are incident to undirected edges. For more details, check component U in partitionLMG.

i1 : U = graph {{1,2},{2,3}}

o1 = Graph{1 => {2}   }
           2 => {1, 3}
           3 => {2}

o1 : Graph
 
i2 : B = bigraph{{4,5}}

o2 = Bigraph{4 => {5}}
             5 => {4}

o2 : Bigraph
 
i3 : D = digraph {{1,4}}

o3 = Digraph{1 => {4}}
             4 => {}

o3 : Digraph
 
i4 : R = gaussianRing mixedGraph(U,B,D)

o4 = R

o4 : PolynomialRing
 
i5 : R.gaussianRingData

o5 = HashTable{compU => {1, 2, 3}}
               compW => {4, 5}
               kVar => k
               lVar => l
               nn => 5
               pVar => p
               sVar => s

o5 : HashTable

Since the gaussian rings of graphs of classes Digraph and Bigraph are created by first changing the class to MixedGraph, the key compU is also present in the gaussianRingData hashtables of these two classes of graphs and the corresponding value is computed according to the rules described in partitionLMG.

i6 : U = graph {{1,2},{2,3}}

o6 = Graph{1 => {2}   }
           2 => {1, 3}
           3 => {2}

o6 : Graph
 
i7 : B = bigraph{{4,5}}

o7 = Bigraph{4 => {5}}
             5 => {4}

o7 : Bigraph
 
i8 : D = digraph {{1,4}}

o8 = Digraph{1 => {4}}
             4 => {}

o8 : Digraph
 
i9 : R1 = gaussianRing B

o9 = R1

o9 : PolynomialRing
 
i10 : R2 = gaussianRing D

o10 = R2

o10 : PolynomialRing
 
i11 : R1.gaussianRingData

o11 = HashTable{compU => {}    }
                compW => {4, 5}
                kVar => k
                lVar => l
                nn => 2
                pVar => p
                sVar => s

o11 : HashTable
 
i12 : R2.gaussianRingData

o12 = HashTable{compU => {}    }
                compW => {1, 4}
                kVar => k
                lVar => l
                nn => 2
                pVar => p
                sVar => s

o12 : HashTable

See also

For the programmer

The object compU is a symbol.