tuned: more direct string comparison (see also 6e25f82056ad, where the explanation was actually wrong: about fast_string_ord instead of string_ord);

--- a/src/HOL/Tools/Sledgehammer/sledgehammer_atp_systems.ML	Tue Jan 07 20:32:15 2025 +0100
+++ b/src/HOL/Tools/Sledgehammer/sledgehammer_atp_systems.ML	Tue Jan 07 20:47:42 2025 +0100
@@ -204,10 +204,10 @@
 
 val old_e_config : atp_config = make_e_config default_max_new_mono_instances (let
        val (format, type_enc, lam_trans, extra_options) =
-         if is_greater_equal (string_ord (getenv "E_VERSION", "3.0")) then
+         if getenv "E_VERSION" >= "3.0" then
            (* '$ite' support appears to be unsound. *)
            (THF (Monomorphic, {with_ite = false, with_let = false}, THF_Without_Choice), "mono_native_higher", keep_lamsN, "--auto-schedule=4 --serialize-schedule=true --demod-under-lambda=true")
-         else if is_greater_equal (string_ord (getenv "E_VERSION", "2.6")) then
+         else if getenv "E_VERSION" >= "2.6" then
            (THF (Monomorphic, {with_ite = false, with_let = false}, THF_Without_Choice), "mono_native_higher", keep_lamsN, "--auto-schedule")
          else
            (THF (Monomorphic, {with_ite = false, with_let = false}, THF_Lambda_Free), "mono_native_higher", combsN, "--auto-schedule")