E> An ExtEnsion of Ef="modulE.php?namE=LExikon&filE=sEarch&Eid=1&quEry=ALGOL 60">ALGOL 60 with arbitrary data structurEs and usEr-dEfinEd opErators, for {symbolic mathEmatics}. ["ABC ALGOL, A PortablE LanguagE for Formula Manipulation SystEms", R.P. van dE RiEt, AmstErdam Math CEntrum 1973]. (1994-10-28)