The new Gödel Prize winner tastes great and is less filling
14 comments
·June 9, 2025bhasi
Eshan's Bachelor's thesis advisor from IIT Kanpur, Prof Manindra Agrawal, also won the Gödel prize in 2006. Wow.
doctorpangloss
It’s tough. You take Math 55, you’re a smart kid, you learn all this math, and it opens up all these opportunities from VCs in the real world for you, so long as it has to do with payments.
antics
If I give you a biased coin can you simulate a truly random coin flip with it? The answer turns out to be yes. Flip the biased coin twice: HT = heads, TH = tails, and HH/TT = flip twice again.
The general study of such things is called “randomness extractors”. The new Gödel prize goes to this paper which shows how to extract a nearly perfect random bit out of two sources with low min-entropy.
pbhjpbhj
Speaking from complete ignorance, with apologies to those who that will annoy:
I'm sure it's possible to make a coin with what one might term "complex bias" where the bias extends over two events (thick gloop inside the coin, possibly heat activated or non-Newtonian).
This method sounds like the bias needs to be fixed ("simple bias" if you like)?
I guess that's just out of scope here.
Aside: There's a strong 'vibe' that HHHH HHHH with a single coin is somehow less random than HTHTHTHT HTHTHTHT with two coins when discarding HH and TT. I wonder what the origin of that feeling is - maybe just HT doesn't seem like it's a constant result simply due to nomenclature? If we call HT "type-A", then we just have HHHH HHHH vs. AAAA AAAA; and I _feel_ happier about the result!
falcor84
Yes, but - you need to replace "twice" there with "an unbounded number of times". If you apply this in an environment where the biased coin is coming from an external source, your system becomes susceptible to DoS attacks.
antics
While I obviously think randomness extractors over adversarial sources are very interesting, I think talking about them specifically in this example complicates the point I'm trying to make, which is that it's incredible it can be done at all.
dataflow
Note that adversarial is kind of a red herring, not sure why they mentioned that. The number of flips is unbounded regardless. Which is why it's not really incredible that it can be done: it can't, not as the problem was originally stated. What can be done is solving a different (but useful) problem than the one originally posed.
I realize this sounds like a minor detail to someone who finds this cool (and so do I), but I don't think it is. It's kind of frustrating to be told that your intuition is wrong by someone smarter than you, when your intuition is actually correct and the experts are moving the goalposts. IMO, it makes people lose respect for experts/authority.
null
Wow, crazy randomly seeing my Algo prof at the top of HN winning this! Congrats Eshan!!