We study a class of \emph{``wave-style'' Geometry of Interaction}
(GoI) $\lambda$-models based on the category \emph{Rel} of sets and
relations.  Wave GoI models arise when Abramsky's GoI axiomatization,
which generalizes Girard's original GoI, is applied to a traced
monoidal category with the \emph{categorical product} as tensor, using
``countable power'' as the traced strong monoidal functor~\bang.\
Abramsky hinted that the category \emph{Rel} is the basic setting for
traditional denotational ``static semantics''.  However, \emph{Rel},
together with the cartesian product, apparently escapes Abramsky's
original GoI construction. Here we show that \emph{Rel} can be
axiomatized as a \emph{strict GoI situation}, i.e. a strict variant of
Abramsky's GoI situation, which gives rise to a rich class of
\emph{strict graph models}.  These are models of \emph{restricted}
$\lambda$-calculi in the sense of \cite{HL99}, such as Church's
$\lambda$-I-calculus and the $\lambda\beta_{KN}$-calculus.  \\ {\bf
Keywords:} (linear) graph model, traced monoidal category, weak linear
category, categorical geometry of interaction.