| 1 |
({m:Msg(w.M)| source(mlnk(m)) = i } List) r (Msg
(( l,tg. da(rcv(l; tg))?Top)) List)
 | 1 step |
| 2 |
31. ({m:Msg(w.M)| source(mlnk(m)) = i } List) r (Msg
31. (( l,tg. da(rcv(l; tg))?Top)) List)
mapfilter(( x.<l,x>) o ( ms.2of(ms)); ms.mlnk(ms) = l;m(i;t))
=
filter( ms.mlnk(ms) = l;m(i;t))
{m:Msg(w.M)| source(mlnk(m)) = i } List
 | 21 steps |
| 3 |
31. ({m:Msg(w.M)| source(mlnk(m)) = i } List) r (Msg
31. (( l,tg. da(rcv(l; tg))?Top)) List)
( x.<l,x>) o ( ms.2of(ms))
{x:{m:Msg(w.M)| source(mlnk(m)) = i }| ( ms.mlnk(ms) = l)(x) }
{m:Msg(w.M)| source(mlnk(m)) = i }
 | 1 step |