Examples of using Cycle basis in English and their translations into Russian
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An integral cycle basis is a set of simple cycles that generates this group.
As a linearly independent set of enough cycles, it necessarily forms a cycle basis.
If every cycle basis of a graph is weakly fundamental, the same is true for every minor of the graph.
As Horton showed, every cycle in the minimum weight cycle basis is a Horton cycle. .
Every graph has a cycle basis in which every cycle is an induced cycle. .
Alternatively, if the edges of the graph have positive weights, the minimum weight cycle basis may be constructed in polynomial time.
A fundamental cycle basis is automatically weakly fundamental for any edge ordering.
For graphs properly embedded onto other surfaces so that all faces of the embedding are topological disks,it is not in general true that there exists a cycle basis using only face cycles. .
The minimum weight cycle basis of a planar graph corresponds to the Gomory-Hu tree of the dual graph.
It states that a finite undirected graph is planar if and only if the cycle space ofthe graph(taken modulo 2) has a cycle basis in which each edge of the graph participates in at most two basis vectors.
A cycle basis of the graph is a set of simple cycles that forms a basis of the cycle space.
Based on this duality, an implicit representation of the minimum weight cycle basis in a planar graph can be constructed in time O( n log 4 n){\displaystyle On\log^{4}n.
A cycle basis is a basis of this vector space in which each basis vector represents a simple cycle. .
It follows that a collection of cycles is a fundamental cycle basis if and only if it has the same property and has the correct number of cycles to be a basis. .
A cycle basis constructed in this way is called a fundamental cycle basis or strongly fundamental cycle basis. .
Using Dijkstra's algorithm to find eachshortest path tree and then using Gaussian elimination to perform the testing steps of the greedy basis algorithm leads to a polynomial time algorithm for the minimum weight cycle basis.
Every cycle basis of a given graph has the same number of cycles, which equals the dimension of its cycle space.
Subsequent researchers have developed improved algorithms for this problem,reducing the worst-case time complexity for finding a minimum weight cycle basis in a graph with m{\displaystyle m} edges and n{\displaystyle n} vertices to O( m 2 n/ log n){\displaystyle Om^{2}n/\log n.
The minimum weight cycle basis of a nearest neighbor graph of points sampled from a three-dimensional surface can be used to obtain a reconstruction of the surface.
Mac Lane's planarity criterion uses this idea to characterize the planar graphs in terms of the cycle bases: a finite undirected graph is planar if andonly if it has a sparse cycle basis or 2-basis, a basis in which each edge of the graph participates in at most two basis cycles.
It is always a weakly fundamental cycle basis, and is fundamental if and only if the embedding of the graph is outerplanar.
A fundamental cycle basis may be formed from any spanning tree or spanning forest of the given graph, by selecting the cycles formed by the combination of a path in the tree and a single edge outside the tree.
There exists a tree for which a given cycle basis is fundamental if and only if each cycle contains an edge that is not included in any other basis cycle.
A cycle basis is called weakly fundamental if its cycles can be placed into a linear ordering such that each cycle includes at least one edge that is not included in any earlier cycle. .
The minimum weight basis of the cycle space is necessarily a cycle basis: by Veblen's theorem, every Eulerian subgraph that is not itself a simple cycle can be decomposed into multiple simple cycles, which necessarily have smaller weight.
In a planar graph, the cycle basis formed by the set of bounded faces is necessarily sparse, and conversely, a sparse cycle basis of any graph necessarily forms the set of bounded faces of a planar embedding of its graph.
If negative weights and negatively weighted cycles are allowed, then finding a minimum cycle basis(without restriction) is also NP-hard, as it can be used to find a Hamiltonian cycle: if a graph is Hamiltonian, and all edges are given weight -1,then a minimum weight cycle basis necessarily includes at least one Hamiltonian cycle. .
Ja'Ja' and Simon start with a fundamental cycle basis of the graph(a cycle basis generated from a spanning tree by forming a cycle for each possible combination of a path in the tree and an edge outside the tree) and transform it into a 2-basis of peripheral cycles. .
The minimum weight cycle basis for a planar graph is not necessarily the same as the basis formed by its bounded faces: it can include cycles that are not faces, and some faces may not be included as cycles in the minimum weight cycle basis. .
However, there exists a minimum weight cycle basis in which no two cycles cross each other: for every two cycles in the basis, either the cycles enclose disjoint subsets of the bounded faces, or one of the two cycles encloses the other one.