The Sweet Science
Like a game of chess, a boxing match has an infinite number of combinations and different ways a fight can play out.
In the beginning of your development, I find it much more important to understand themes (changing levels/speed, countering and feinting, fighting on the inside vs the outside, etc) than to just memorize combinations. Just like in chess you learn basic strategies and tactics (center control, when to castle, forks, pins, discovered openings, etc) before memorizing openings.