Two teen players filled gaps in London

A particularly interesting side event was staged concurrently with the recent World Championship Candidates' semifinal matches in the Great Eastern Hotel in London. It featured a match between 19-year-old Joel Benjamin, a Yale junior and international master from Brooklyn, N.Y., and his British counterpart, 18 -year-old Nigel Short, also an international master with top credentials. Benjamin, arguably the strongest non-grandmaster in the world, convincingly overwhelmed Short by winning four games and drawing three (51/2-11/2).

The margin of victory was bewildering, since Short had beaten the American in three previous encounters and had been enjoying a hot streak in recent events. The match was unrated, being played at a somewhat faster and more irregular pace than usual.

The players were whisked down to the stage to fill in for the candidates whenever they happened to be peacefully inclined, and Acorn Computers, which sponsored the candidates matches, awarded Benjamin (STR)400 ($560) and Short (STR)300 for their efforts.

The following game shows Short, behind in the match, unwisely selecting a dubious but complicated opening made to order for Benjamin's trenchant style. Modern Benoni

Benjamin Short 1. P-Q4 N-KB3 2. P-QB4 P-K3 3 N-KB3 P-B4 (a) 4. P-Q5 PxP 5. PxP P-Q3 6. N-B3 P-KN3 7. N-Q2 QN-Q2 8. P-K4 B-N2 9. B-K2 O-O 10. O-O R-K1 11. P-QR4 N-K4 12. Q-B2 P-KN4 (b) 13. R-K1 P-N5 14. N-B1 N-R4 15. B-Q2 Q-B3 16. N-N3 N-B5 17. N-B5 NxB ch 18. NxN BxN 19. PxB Q-R5 20. N-N3 P-B5 21. B-B3 QR-B1 22. R-K4 P-QR3 23. P-B6 (c) QxP 24. RxNP NxR (d) 25. BxQ NxB 26. N-B5 B-B1 27. Q-Q2 K-R1 28. P-B4 K-N1 29. R-R3 P-R3 30. R-N3 ch K-R2 31. Q-Q4 N-R4 32. R-KR3 K-N3 33. RxN KxR 34. Q-B6 K-N5 35. K-B2 KxP 36. N-N3 ch Resigns

A. Introduces the popular Benoni, wherein Black usually obtains an extra pawn on the Queenside by allowing White an extra pawn in the center.

B. Double-edged and typical of Black's strategy in this opening. He maintains the position of his Knight at K4 but weakens his own KB4. We will see how Benjamin cleverly exploits this on his 23rd move.

C. A clever vacating sacrifice. Now if 23. . . . BxP, then 24. N-B5 and 25. NxQP, and White gains the exchange with an easy win.

D. As good or as bad as any, since Black has no viable defense against the threatened 25. N-R5.