  Strand spaces are a popular framework for the analysis of security protocols.
Strand spaces have some similarities to a formalism used successfully to model
protocols for distributed systems, namely multi-agent systems. We explore the
exact relationship between these two frameworks here. It turns out that a key
difference is the handling of agents, which are unspecified in strand spaces
and explicit in multi-agent systems. We provide a family of translations from
strand spaces to multi-agent systems parameterized by the choice of agents in
the strand space. We also show that not every multi-agent system of interest
can be expressed as a strand space. This reveals a lack of expressiveness in
the strand-space framework that can be characterized by our translation. To
highlight this lack of expressiveness, we show one simple way in which strand
spaces can be extended to model more systems.
