In 2010, Alpert et al. [1] introduced the concept of obstacle representation of a graph G. The obstacle representation of G is about assigning points in R~2 for each vertex of G and blocking the visibility among pairs of points whose corresponding vertices do not have an edge. In the Euclidean plane, the shortest path and straight line visibility are essentially the same. We introduce a new definition of obstacle representation in Z~d as follows; this can be generalized to any metric space as given in [3, 4].
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