# Retrieve all author names
function test (map $m) as list return {
    forall [ (is-author-of)
             author : $a ]
     =>  exists [ $a
                  bn@uc: $bn ] in $m
    return
       ($bn)
}
# Retrieve all author names, short solution
function test (map $m) as list return {
    forall [ (is-author-of)
             author : $a ] in $m
    return
       ($a/bn@uc)
}
# using AsTMaPath only
function test (map $m) as list return
  ($m / is-author-of / author/bn @uc)