1. Differential notation is confusing
"What does it mean with his d() operator to divide by dx? All of a sudden it seems like he has changed dy/dx from unfortunate notation that sort of looks like a division into something that actually is dividing two meaningful things, dy and dx? And so what the hell are dy and dx?" – cool_dude85
2. “Senior Engineer” title is a tongue‑in‑cheek reference
"Looks like this came out nearly 8 years ago, so… how’d it work out? Given the way job titles work these days I guess we could have some Senior Engineers here who learned calculus from this paper…" – bee_rider
3. Teaching calculus needs a revamped approach
"The limit of a function f at a point x is defined as the value y, if it exists, such that for all d > 0 there exists an e > 0 such that for all x' in [x - e, x + e] we have |y - f(x')| < d. That's an earful." – scythe