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{\bf Guantao Chen, Ralph J. Faudree and Ronald J. Gould}
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{\bf Saturation Numbers of Books}
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A book $B_p$ is a union of $p$ triangles sharing one edge.
This idea was extended to a generalized book $B_{b,p}$, which is
the union of $p$ copies of a $K_{b+1}$ sharing a common $K_b$.
A graph $G$ is called an $H$-saturated graph if $G$ does not
contain $H$ as a subgraph, but $G\cup \{xy\}$ contains a copy of
$H$, for any two nonadjacent vertices $x$ and $y$. 
The {\it saturation number of $H$}, denoted by $sat(H,n)$, is
the minimum number of edges in $G$ for all $H$-saturated graphs $G$
of order $n$.   We show that 
$$
sat(B_p, n) = {1\over2} \big( (p+1)(n-1) 
- \big\lceil {p\over2}\big\rceil \big\lfloor {p\over2} \big\rfloor + \theta(n,p)\big),
$$
where $\theta(n, p) = \cases{ 
1& \hbox{ if $p\equiv n -p/2 \equiv 0 \bmod 2$} \cr
0& \hbox{ otherwise}
}$,
provided $n \ge p^3  + p$. 

Moreover, we show that 
$$\eqalign{
sat(B_{b,p}, n) = \ & {1\over2} 
\big( (p+2b-3)(n-b+1) - \big\lceil {p\over2}\big\rceil 
\big\lfloor {p\over2} \big\rfloor\cr 
&+ \theta(n,p, b)+(b-1)(b-2) \big),\cr}
$$
where $\theta(n, p, b) = \cases{ 1& \hbox { if $ p \equiv n -p/2
-b \equiv 0 \bmod 2$} \cr
 0 & \hbox{ otherwise}
}$,
provided $n \ge 4(p+2b)^{b}$. 




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