@techreport{men-xav-far-fig-sto-99-vdel-tr,
  author = {C{\^a}ndido F. Xavier de {Mendon{\c{c}}a Neto} and {\'E}rico F. {Xavier} and Lu{\'e}rbio Faria and Celina M. H. de Figueiredo and Jorge Stolfi},
  title = {The Vertex Deletion Number of {$C_n \times C_m$}},
  institution = {Institute of Computing, Univ. of Campinas},
  number = {IC-99-14},
  pages = {39},
  year = 1999,
  month = may,
  abstract = {The vertex deletion number of a graph $G$ is the smallest integer $k \geq 0$ such that there is a planar induced subgraph of $G$ obtained by the removal of $k$ vertices from $G$. In this work we study the vertex deletion number of $C_n\times C_m$, the rectangular grid with toroidal topology. We prove the extact result $\min\{n,m\} - \xi_{5,9}(n,m)$, where $\xi_{i,j}(k_1,k_2)$ is the number of true conditions among the following: (i) $k_1 = k_2 \leq i$ and (ii) $k_1 + k_2 \leq j$.}
}