  A $\textit{knot}$ is a possibly wild simple closed curve in $S^3$. A knot $J$
is $\textit{semi-isotopic}$ to a knot $K$ if there is an annulus $A$ in
$S^3\times[0,1]$ such that $A\cap(S^3\times\{0,1\})=\partial
A=(J\times\{0\})\cup(K\times\{1\})$ and there is a homeomorphism
$e:S^1\times[0,1)\rightarrow A-(K\times\{1\})$ such that
$e(S^1\times\{t\})\subset S^3\times\{t\}$ for every $t\in[0,1)$.
  $\textbf{Theorem.}$ Every knot is semi-isotopic to an unknot.
