Great Ideas in Theoretical Computer Science

Theory class sparks chaos: weed-out whispers, zero highlights, cheat-code hype

TLDR: A theory-first CS course explains how computers work—from simple models to Turing machines—and why some problems can’t be solved. Comments split between “weed-out” accusations and fans praising math and “cheat-code” randomness, sparking a louder debate over whether CS should prioritize proofs and limits or real-world practicality.

A new open course promises the “great ideas” of how computers — and maybe the universe — compute: from simple toy machines to Turing machines (an abstract stand‑in for any computer) and the big twist that some questions can never be answered. But the comments went full drama. One reader swears CMU treated it as “a weed‑out class,” igniting the age‑old fight: brain‑stretching essentials or gatekeeping? Another roasted the empty “Highlights” section as the most honest syllabus ever. And a war story stole the show: when asked for practical use, a prof allegedly replied, “I don’t really care,” reminding everyone this is science class, not a startup pitch.

Then came the counterpunch. Theory fans piled in to say this stuff matters, period. A stan hyped randomized algorithms as feeling like cheating past famously hard problems—cue memes about math cheat codes. Old‑timers dropped receipts to a previous 93‑comment brawl. Verdict: the thread split between “weed‑out cruelty,” “highlight‑free honesty,” and “pure‑math joy.” Behind the jokes is a real question: should CS teach limits and proofs first, or keep it practical? Whichever side you’re on, this class just became the latest culture war over what computer science is for.

Key Points

  • The course formalizes computation and algorithms, starting from data representation and problem definition.
  • Deterministic finite automata (DFA) are introduced as a simple model with applications and a foundation for algorithm definition.
  • Turing machines are defined as the standard model of computation, linked to the physical Church–Turing thesis.
  • The course proves most problems are undecidable, demonstrating explicit examples using diagonalization and reductions.
  • Historical context connects formalization of mathematics to formalizing computation, while noting many practical problems are decidable.

Hottest takes

a “weed-out class” — Ifkaluva
"I don't really care." — Neywiny
They really feel like cheating your way out of NP problems. — skulk
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