I think maybe the concept of () vs [] for radio buttons and checkboxes respectively is in part due to the mathematical concept of a bounded number range where t

I think maybe the concept of () vs [] for radio buttons and checkboxes respectively is in part due to the mathematical concept of a bounded number range where the numbers at the end of the range are included inclusively or exclusively. I'm not saying they're the same concept, but that it might have inspired their usage. Just a theory.