Computer Scientists Close In on Unique Games Conjecture Proof | Quanta Magazine

news org:mag org:sci popsci tcs cs computation UGC complexity approximation lower-bounds hardness nibble org:inst rand-approx proofs big-surf announcement SDP optimization open-problems questions research

june 2018 by nhaliday

news org:mag org:sci popsci tcs cs computation UGC complexity approximation lower-bounds hardness nibble org:inst rand-approx proofs big-surf announcement SDP optimization open-problems questions research

june 2018 by nhaliday

Cryptography at STOC/FOCS | in theory

june 2016 by nhaliday

On Sunday I also attended a cryptography session. One thing that impressed me was the lively discussion at the end of the talks, very different from the stunned silence that usually follows when the session chair asks if there are any questions. The other thing I noticed was that the session was attended almost exclusively by cryptographers.

Why is that? A first guess is that the field has become very technical. But this cannot be the point; after all, a typical paper on PCP is also very technical, but the audience is not made exclusively of PCP technicians. Maybe the point is that even, or especially, definitions are very technical in cryptography. One can go to a talk showing that sparsest cut does not have a constant-factor approximation assuming the Unique Games Conjecture, and be fairly satisfied that he understands what it would mean for sparsest cut to have a constant-factor approximation and what it would mean for the Unique Games Conjecture to be false. Then one sees some slides with clouds of vertices connected in various ways, one hears mentions of Gaussian distributions, influence of variables, and invariance principles, and one gets lost, but with an idea that there is a reduction that needs certain complicated mathematical techniques to be analyzed.

In a cryptography talk, however, one may get started with the problem of realizing primitive X under assumptions Y1 and Y2, according to security requirement Z, with no set-up assumptions, and it would require quite some expertise to realize that requirement Z is considerably harder to achieve than similarly sounding Z’, which was known to be achievable under assumptions of Y1 and Y’2, where Y’2 is incomparable to Y2, but intuitively stronger, and so on. Consider the recent breakthrough on the long-standing very clear-cut question to achieve statistically hiding commitments assuming only one-way functions. This is a statement that is an order of magnitude simpler than the typical result in cryptography, probably the most basic question that was still open in the 2000s, but even to unpack such a statement is not easy and requires to see various examples, discussion of applications and so on.

crypto
rigorous-crypto
research
thinking
tcs
critique
reflection
tcstariat
conference
lens
UGC
boolean-analysis
reduction
conceptual-vocab
ground-up
luca-trevisan
nibble
org:bleg
stoc
focs
Why is that? A first guess is that the field has become very technical. But this cannot be the point; after all, a typical paper on PCP is also very technical, but the audience is not made exclusively of PCP technicians. Maybe the point is that even, or especially, definitions are very technical in cryptography. One can go to a talk showing that sparsest cut does not have a constant-factor approximation assuming the Unique Games Conjecture, and be fairly satisfied that he understands what it would mean for sparsest cut to have a constant-factor approximation and what it would mean for the Unique Games Conjecture to be false. Then one sees some slides with clouds of vertices connected in various ways, one hears mentions of Gaussian distributions, influence of variables, and invariance principles, and one gets lost, but with an idea that there is a reduction that needs certain complicated mathematical techniques to be analyzed.

In a cryptography talk, however, one may get started with the problem of realizing primitive X under assumptions Y1 and Y2, according to security requirement Z, with no set-up assumptions, and it would require quite some expertise to realize that requirement Z is considerably harder to achieve than similarly sounding Z’, which was known to be achievable under assumptions of Y1 and Y’2, where Y’2 is incomparable to Y2, but intuitively stronger, and so on. Consider the recent breakthrough on the long-standing very clear-cut question to achieve statistically hiding commitments assuming only one-way functions. This is a statement that is an order of magnitude simpler than the typical result in cryptography, probably the most basic question that was still open in the 2000s, but even to unpack such a statement is not easy and requires to see various examples, discussion of applications and so on.

june 2016 by nhaliday

Hypercontractivity and its Applications | tcs math

tcs tcstariat washington papers slides survey talks lectures exposition concept estimate math boolean-analysis yoga cool rand-approx optimization algorithms coding-theory math.GR SDP rounding complexity lower-bounds graphs graph-theory UGC org:bleg nibble

may 2016 by nhaliday

tcs tcstariat washington papers slides survey talks lectures exposition concept estimate math boolean-analysis yoga cool rand-approx optimization algorithms coding-theory math.GR SDP rounding complexity lower-bounds graphs graph-theory UGC org:bleg nibble

may 2016 by nhaliday

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