Carlsen - Nepomniachtchi 11 years before

Both participants celebrated their E-jubilee this year. The letter E here stands for Natural Anniversary. 31 is a prime number. It is divisible only by one and by itself. A series of primes starts with 1 and continues like this 2 3 5 7 11 13 17 19 23 29 31 ... 37 43 47, etc.