Ukrainian grandmaster Ruslan Ponomariov continues to lead at the international chess tournament in Sofia. In the seventh-round match, he played to a draw with black pieces against Judit Polgar of Hungary. In other matches of this round, Bulgarian Veselin Topalov defeated England's Michael Adams, and Viswanathan Anand of India won against Russia's Vladimir Kramnik.   With three rounds remaining before the end of the competition, Ponomariov and Topalov are in the lead, having each scored 4 points. Anand and Polgar have 3.5 each, while Kramnik and Adams have 3 points each.