Anatoly Karpov resigned game 13 of his world championship chess match without resuming play, as predicted in yesterday's report, giving challenger Victor Korchnoi a new lease on life. Karpov sent a note to match officials about an hour before the game was scheduled to resume, saying simply (in English), "Hereby I inform you that I resign the 13th game without resuming play."

The situation, with a queen and two pawns against a rook and four pawns, is one that has not been much analyzed by chess theoreticians, and the complications of the position could have kept the game going for a long time. There are some situations where a rook and pawn alone can force a draw against a queen with no pawns -- but apparently overnight analysis by Karpov's team showed that he could not reach such a position.

The score now stands at 4 to 2, still in Karpov's favor. But chess fans in Merano, Italy, where the match is taking place, are beginning to talk about the last Karpov-Korchnoi match, three years ago, when Korchnoi was trailing at one point by a score of 5 to 2 and equalized at 5 to 5 before losing by 6 to 5. Korchnoi's present negative score is a result of the disastrous beginning of the match, when he lost three of the first four games. The score for the last nine games has been 2 to 1 in his favor, with six draws.

Chess experts in Merano seem largely agreed that the two Korchnoi victories are the most interesting games so far in the match, along with game 11 -- a draw, but a game in the Korchnoi style, packed with action and interesting complications.

Lev Polugaevsky, a Soviet grandmaster who was a candidate for the world championship and is in Merano as part of Karpov's team, called game 13 "the prettiest game yet, a beautiful battle of tactics."

Game 14 is scheduled to begin tomorrow, but it is considered likely that Karpov will ask for a postponement.