KIEV — Ukraine's Supreme Court yesterday rejected four more challenges to President-elect Viktor Yuschenko's polling victory, removing a final legal barrier to official announcement of his victory. The court refused to review the claims filed by Prime Minister Vikor Yanukovich, the loser in the December 26 poll, on procedural grounds. There is no appeal. The Central Election Committee was expected to announce Yuschenko's victory later.ÂÂ