prove one more lemma using Sledgehammer, with some guidance, and replace clumsy old proof that relied on old extensionality behavior

fixed several bugs in Isar proof reconstruction, in particular w.r.t. mangled types and hAPP

another concession to backward compatibility

no need to use metisFT for Isar proofs -- metis falls back on it anyway

handle equality proxy in a more backward-compatible way

remove problematic Isar proof

added two mildly higher-order examples contributed by TN, removed references to obsoleted type systems, and moved things around

robustly detect how many type args were passed to the ATP, even if some of them were omitted

make sure "simple_types_query" and "simple_types_bang" symbols are declared with the proper types

drop some type arguments to constants in unsound type systems + remove a few type systems that make no sense from the circulation

tuning

fixed conjecture resolution bug for Vampire 1.0's TSTP output

ensure Set.member isn't introduced by Meson's preprocessing if it's supposed to be unfolded

Metis doesn't find an old proof in acceptable time now that higher-order equality reasoning is supported -- tuned proof script to help it

drop support for Vampire's native output format -- it has too many undocumented oddities, e.g. "BDD definition:" lines

use the same code for extensionalization in Metis and Sledgehammer and generalize that code so that it gracefully handles negations (e.g. negated conjecture), formulas of the form (%x. t) = u, etc.

further lower penalty associated with existentials in Sledgehammer's relevance filter, so that "exhaust" facts are picked up

reenabled equality proxy in Metis for higher-order reasoning

added "SMT." qualifier for constant to make it possible to reload "smt_monomorph.ML" from outside the "SMT" theory (for experiments) -- this is also consistent with the other SMT constants mentioned in this source file

reflect option renaming in doc + do not document the type systems poly_preds? and poly_tags?, since they are virtually identical to the non-? versions

unfold set constants in Sledgehammer/ATP as well if Metis does it too

do not pollute relevance filter facts with too many facts about the boring set constants Collect and mem_def, which we might anyway unfold depending on Meson's settings

renamed "max_mono_instances" to "max_new_mono_instances" and changed its semantics accordingly

added unfold set constant functionality to Meson/Metis -- disabled by default for now

remove unused parameter

reduced penalty associated with existential quantifiers

ensure that Auto Sledgehammer is run with full type information

fine-tuned the relevance filter, so that equations of the form "c = (%x. _)" and constants occurring in chained facts are not unduely penalized

don't give weights to built-in symbols

more robust exception handling in Metis (also works if there are several subgoals)