ITALY'S COMMUNIST PARTY convenes a special congress Thursday to drop the word "Communist" from its name. . . . INDONESIAN FOREIGN MINISTER Ali Alatas left for Hanoi Thursday to continue his efforts to settle the 12-year-old Cambodian conflict that sparked by Vietnam's invasion of Cambodia in late 1978. . . . CHINESE POLICE HAVE determined that a recent explosion in downtown Tiananmen Square was caused by a home-made bomb, apparently set off as a gesture of protest against the hard-line regime.