BOSTON (AP) — Jayson Tatum had 31 points, 11 assists and eight rebounds as the Celtics topped the Dallas Mavericks 106-88 to claim the franchise’s 18th championship, breaking a tie with the Los Angeles Lakers for the most in league history. Boston earned its latest title on the 16th anniversary of hoisting its last Larry O’Brien Trophy in 2008. It marks the 13th championship won this century by one of the city’s Big 4 professional sports franchises. Jaylen Brown added 21 points. Jrue Holiday finished with 15 points and 11 rebounds. Luka Doncic finished with 28 points and 12 rebounds for Dallas, which failed to extend the series after avoiding a sweep with a 38-point win in Game 4.