"accessible" . . "Stallings' ends theorem" . . . "a theorem of Stallings" . "Stalling's theorem" . "Freudenthal-Hopf theorems" . "Stallings theorem about ends of groups" . "one-ended" . "splittings and accessibility of discrete groups" . "Stallings' theorem about ends of groups" . "Stallings' theorem" . . "Stallings theorem about ends of groups" . . . . .