doc-src/Tutorial/Misc/InfixTree.ML

theorem database now also indexes constants "Trueprop", "all",
"==>", "=="; thus thms_containing, findI etc. may retrieve more rules;

Goal "!xs. linInfixList t xs = infixList t @ xs";
by(induct_tac "t" 1);
by(Simp_tac 1);
by(Asm_simp_tac 1);