Associations connect Actors and use cases via solid lines. Every actor must communicate with at least one use case. An association is always binary and multiplicities may be specified.
graph {
nodesep=0.8
subgraph cluster0 {
label = "Laboratory Assignment"
c [label="Conduct oral exam"]
}
c--a
c--s [label="1..3"]
a [shape=star label="" xlabel="Assistant"]
s [shape=star label="" xlabel="Student"]
}