because some graphs that have the “many to one” situation aren’t necessarily going to be functions; There may be other places (i.e. a couple of other coordinate points) that connect vertically, therefore disqualifying it as a function. These “rules” can also bedifficult to remember...
summable function) has an integrable absolute value. “Integrable” means that you can find anintegral. The “Absolutely” portion of the term refers to the fact that it’s theabsolute value of the functionthat must be integrable on thereal line(Feeman, 2015). In notation, we can write ...