I have a set of NBA matches (both regular and playoffs) and their dates and I need to determine which season they belong to. I was thinking of having an interval for each season that the matches are guaranteed to be between, but I don't know what that would be.
If you are just looking to determine which year a match belongs to, there are never any NBA games in July, August, or September. August 1 would be a safe date to pick as the cutoff between seasons.
If you need to determine whether a match is a regular season game or a playoff game, the dates are different every year.
Basketball-reference.com has a complete listing of every game, going all the way back to the 1946-47 season of the Basketball Association of America, the former name of the NBA.
This is a list of every season of the NBA and ABA. Click on the year of the season you are interested in. Then click on the "Schedule & Results" tab to see the list of every regular season and post-season game.
For example, the 1970-71 season began on Tuesday, October 13, 1970. The last regular season game was Tuesday, March 23, 1971. The playoffs began on Wednedsay, March 24, 1971 and ended when the Milwaukee Bucks beat the Baltimore Bullets on Friday, April 30, 1971, with Kareem Abdul-Jabbar as the MVP.