Thread:Theundeadlord/@comment-16107481-20151208193919/@comment-16107481-20151209063015

Exactly.

Example; to Summon "Border Limit Bound Dragon" (whose infimum is 1000 and supremum is 2000), you need to send 1 Element monster from your side of the field to the Graveyard whose ATK is between 1000 and 2000. You can send "Batteryman Li-ion" (whose ATK is 1600), but you can't send "Moon-Enchanting Archer" (whose ATK is 2200).

HINT: Monsters with "tight" infimum and supremum are meant to be stronger, as they are harder to Summon. Monsters with "loose" infimum and supremum are meant to be less powerful, as they are easier to Summon.