Fri, 27 Jul 2018 17:27:42 +0200 wenzelm proper maxidx: if x does not occur in A, its maxidx could get lost;
(0) -30000 -10000 -3000 -1000 -300 -100 -30 -10 -1 +1 +10 +30 +100 +300 +1000 +3000 +10000 tip