  We study computational problems for two popular parliamentary voting
procedures: the amendment procedure and the successive procedure. While finding
successful manipulations or agenda controls is tractable for both procedures,
our real-world experimental results indicate that most elections cannot be
manipulated by a few voters and agenda control is typically impossible. If the
voter preferences are incomplete, then finding which alternatives can possibly
win is NP-hard for both procedures. Whilst deciding if an alternative
necessarily wins is coNP-hard for the amendment procedure, it is
polynomial-time solvable for the successive one.
