In this paper we introduce a new notion of collective tree spanners. We say that a graph G = (V, E) admits a system of µ collective additive tree r-spanners if there is a system T (G) of at most µ spanning trees of G such that for any two vertices x, y of G a spanning tree T ∈ T (G) exists such that dT (x, y) ≤ dG(x, y) + r. Among other results, we show that any chordal graph, chordal bipartite graph or cocomparability graph admits a system of at most log2 n collective additive tree 2–spanners and any c-chordal graph admits a system of at most log2 n collective additive tree (2 c/2 )–spanners. Towards establishing these results, we present a general property for graphs, called (α, r)– decomposition, and show that any (α, r)–decomposable graph G with n vertices admits a system of at most log1/α n collective additive tree 2r– spanners. We discuss also an application of the collective tree spanners to the problem of designing compact and efficient routing schemes in gra...
Feodor F. Dragan, Chenyu Yan, Irina Lomonosov