--- a/src/HOL/ex/HarmonicSeries.thy Thu Aug 27 15:23:48 2020 +0100
+++ b/src/HOL/ex/HarmonicSeries.thy Thu Aug 27 16:48:21 2020 +0100
@@ -280,8 +280,8 @@
then obtain n::nat where ndef: "n = nat \<lceil>2 * ?s\<rceil>" by simp
then have ngt: "1 + real n/2 > ?s" by linarith
define j where "j = (2::nat)^n"
- have "\<forall>m\<ge>j. 0 < ?f m" by simp
- with sf have "(\<Sum>i<j. ?f i) < ?s" by (rule sum_less_suminf)
+ have "(\<Sum>i<j. ?f i) < ?s"
+ using sf by (simp add: sum_less_suminf)
then have "(\<Sum>i\<in>{Suc 0..<Suc j}. 1/(real i)) < ?s"
unfolding sum.shift_bounds_Suc_ivl by (simp add: atLeast0LessThan)
with j_def have