"Is" is not "Not": "Not" is not "Is" <--- a Circular Reasoning Fallacy?

I'm trying to avoid getting into the deeper epistemological and ontological philosophy with the above question, so would like to focus only on the fallacy/validity of it. Having just read your piece on Circular Reasoning, and while within it you do say that completely avoiding it is impossible, you do state that one should avoid, as best as one can, very tight circular arguments. I wondered whether such a 'tight' circular reasoning example (The definition of "Is" as being not "Not") is fallacious from the get-go?

I can accept (or rather, I am currently of the opinion) that "Is" is somehow more dependent upon "Not", in that "not-not" is . From there, we see that "Not" and "is not" are equivalent because "Is not" can be expressed as "not-not not". You see that I'm using 'not' as a base 'atom'. I do not believe (though I haven't tried it yet) that similar arguments can be built with "is" as the 'atomic' entity.

It seems that circular reasoning here is not only not fallacious , it is indeed essential . But am I wrong?

To fully answer this one, it might require a full day of staring at my lava lamp—but I will do my best, focusing on the possible fallaciousness of the "argument."

First, this strays from the standard argument formula and is more of a definition, therefore, calling a fallacy on a definition is a bit strange. If I am understanding this correctly, it is being stated that "is" as being defined as "not not." I am not sure this would fit under circular reasoning, simply because there is not much "reasoning" involved. It is more of a "not very helpful" definition. For example, if I asked you to define "alive" for me, and you responded with "not dead," I would give you a big sarcastic "wow, that was helpful." Similarly, if I wanted to know from a philosophical/epistemological perspective what "is" means, "not not" would not be a satisfying answer, although I would not see this as fault in reasoning.

That is my take, anyway. Hope it is helpful!