  For $1<p<\infty$, we prove (i) a version of Voiculescu's absorption theorem
for operators on $l^{p}$, (ii) that
$\mathrm{Ext}_{\sim,s}(\mathcal{A},K(l^{p}))$ is a group for certain Banach
algebra $\mathcal{A}$, and (iii) homotopy invariance of
$\mathrm{Ext}_{\sim,s}(\mathcal{A},K(l^{p}))^{-1}$ in $\mathcal{A}$ for
separable Banach algebra $\mathcal{A}$ that is isomorphic to a subalgebra of
$B(l^{p})$.
