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We study heteroclinic connections in a nonlinear heat equation that
involves blow-up. More precisely we discuss the existence of $L^1$ connections among
equilibrium solutions. By an $L^1$-connection from an equilibrium $\phi^{-1}$ to an equilibrium
$\phi^+$ we mean a function $u$($.,t$)
which is a classical solution on the interval
$(-\infty,T)$
for some $T\in \mathbb R$ and blows up at $t=T$ but continues to exist in the space $L^1$ in a
certain weak sense for $t\in [T,\infty)$
and satisfies $u$($.,t$)$\to \phi^\pm$
as $t\to\pm\infty$ in a suitable sense.
The main tool in our analysis is the zero number argument;
namely to count the number of intersections between the graph of a given solution and that of various
specific solutions.