## § Stalking syzigies on hackernews

He's the author of Macaulay; I learnt quite a bit by stalking him on hackernews
• Schreier–Sims algorithm for computing with permutations.
• Our phones should learn a private language with us. My dog learns after one repetition; Zoom should learn to arrange my windows as I like, at least after 47 repetitions.
• Our extrapolations always take the form of moving along a tangent vector out from prior experience. Prior to relativity, Newtonian physics was the belief that we actually lived in that tangent space. Surprises come when the deviations are large enough for reality to curve away from our models
• Like flipping through for the soft porn in a friend's "romance" novel, I must confess I searched straight for this guideline.
- Lisp's signature 17 car pileup at the end of every expression.
• I look for the $ or equivalent in any proposal out there, to see if the author has written lots of code or is just talking. It's like looking for bone marrow in beef stew, evaluating a cookbook. Marrow is central to the story of Lisp; we got our start being able to wield tools to crack open bones after lions and jackals had left a kill. The added nutrition allowed our brains to increase in size. Soon we mastered fire, then Lisp. • I spent the first few months outside doing woodworking; I've been struggling with an overwhelming urge to center my consciousness in my hands. This is of course the history of our species, a biological urge as profound as our sex drive. We figured out how to make very sharp hunting tools from unruly rocks, or we died. • The first chapter of Berstel and Reutenauer's "Noncommutative Rational Series with Applications" presents Schützenberger's theorem that every noncommuting rational power series is representable, and conversely. The idea is NOT painfully abstract, but makes twenty minutes work of a semester of undergraduate automata theory (an assertion I've tested multiple times in my math office hours). • You don't want sync software going off and "thinking" about what a symlink really means, anymore than you'd want sync software going off and "thinking" after finding porn on your computer • Luckily, I was trained far enough down the street from MIT to escape their Lisp world view, so we coded our computer algebra system in C, and it was fast enough to succeed and bring us tenure. Today, we'd choose Haskell. His LISP language with inferred parens: define | edge? g e let$ es | edges g
e2 | reverse e
or (member e es) (member e2 es)

(define (edge? g e)
(let
( (es (edges g))
(e2 (reverse e)))
(or (member e es) (member e2 es))))