52 lines
1.3 KiB
PHP
52 lines
1.3 KiB
PHP
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<?php
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namespace Graphp\Algorithms\Property;
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use Graphp\Algorithms\BaseGraph;
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/**
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* Simple algorithms for working with Graph properties
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*
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* @link https://en.wikipedia.org/wiki/Graph_property
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*/
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class GraphProperty extends BaseGraph
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{
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/**
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* checks whether this graph has no edges
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*
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* Also known as empty Graph. An empty Graph contains no edges, but can
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* possibly contain any number of isolated vertices.
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*
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* @return boolean
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*/
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public function isEdgeless()
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{
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return $this->graph->getEdges()->isEmpty();
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}
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/**
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* checks whether this graph is a null graph (no vertex - and thus no edges)
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*
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* Each Edge is incident to two Vertices, or in case of an loop Edge,
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* incident to the same Vertex twice. As such an Edge can not exist when
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* no Vertices exist. So if we check we have no Vertices, we can also be
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* sure that no Edges exist either.
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*
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* @return boolean
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*/
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public function isNull()
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{
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return $this->graph->getVertices()->isEmpty();
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}
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/**
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* checks whether this graph is trivial (one vertex and no edges)
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*
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* @return boolean
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*/
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public function isTrivial()
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{
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return ($this->graph->getEdges()->isEmpty() && count($this->graph->getVertices()) === 1);
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}
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}
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