graph theory

[Brendan McKay]

(Oops, I accidentally sent this to graphnet instead of seqfan ;-).

An even more general concept is to take a graph G and a |VG| copies
of a rooted graph H, then identify vertex i of G with the root of
the i-th copy of H, for each i.  This was called the "rooted product"
by Chris Godsil and myself in a 1978 paper (MR0494910) and the name
has been used regularly (but not very often) since then.

Brendan.

* Edwin Clark <eclark at math.usf.edu> [050108 12:55]:
> 
> Anyhow graph theorists have a somewhat more general concept 
> involving two graphs:
> 
> "The corona $G_1\circ G_2$ of two graphs $G_1$ and $G_2$ was defined by 
> Frucht and Harary as the graph $G$ obtained by taking one copy of $G_1$ 
> which has $p_1$ vertices and $p_1$ copies of $G_2$ and then joining the 
> $i$th vertex of $G_1$ to every vertex in the $i$th copy of $G_2$. 

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