doc-src/Tutorial/Misc/InfixTree.ML

reverted to old proof of dominoes_tile_row, given new treatment of #2+...

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