clarified NEWS: document_files are officially required since Isabelle2014, but the absence was tolerated as legacy feature;
section {* Prefixpoints *}
theory Ex4
imports "../LCF"
begin
lemma example:
assumes asms: "f(p) << p" "\<And>q. f(q) << q \<Longrightarrow> p << q"
shows "FIX(f)=p"
apply (unfold eq_def)
apply (rule conjI)
apply (induct f)
apply (rule minimal)
apply (intro strip)
apply (rule less_trans)
prefer 2
apply (rule asms)
apply (erule less_ap_term)
apply (rule asms)
apply (rule FIX_eq [THEN eq_imp_less1])
done
end