Using Martingales to Derive Robust Concentration Inequalities in Probability Theory
Examining popular concentration inequalities and deriving strengthenings for Martingales.
Mahaney's Theorem on the Conditions for the NP-completeness of Sparse Languages
A pretty interesting implication involving \(\mathrm{P}\), \(\mathrm{NP}\), unary, and sparse languages.
Barrington's theorem for Permutation Branching Programs for \(\mathrm{NC}_1\) languages
Showing that non-uniform \(\mathrm{NC}_1\) language has a polynomial-size width-5 branching program.
A Formal Introduction to Embeddings
Low-dimension embeddings, Bourgain's distortion proofs, and extensions to \(\ell_p\)-spaces.
List Decoding of the BH, RS, and PV Codes
List Decoding is really cool, but it also reveals some spectacular results in complexity theory.
A Mathematical Prank on a Chemist
The saga of how Andrew and I pranked Bill through cyclic shifts during thanksgiving break.
Relations on NL through Undirected ST-connectivity
All problems in \(\mathrm{NL}_i\) have \(O(\log^{2i} n)\) depth, fan-in 2, Boolean circuits through \(\mathrm{USTCON}\).
Why do most chords sound unpleasant to the ear?
A beautiful probabilistic argument for why most chords sound unpleasant to the human ear.
Lipschitz functions and Bernstein polynomials
Showing that Lipschitz functions can be approximated by Bernstein polynomials.
Unraveling the Sipser-Lautemann theorem
Proving that \(\mathrm{BPP}\) is contained somewhere in the intersections of the polynomial hierarchy.
An online algorithm to hire the best candidate
Hiring the best secretary in an online setting with a \(3.6\) röntgen (not great, not terrible) probability.
Proving Toda's Theorem
A proof of Toda's theorem, which is that the polynomial hierarchy can be captured by the ability to count.
Proving the Karp-Lipton theorem
A proof of Karp-Lipton's theorem, which is a surprising statement about the polynomial hierarchy and symmetric quantifiers.
Intersections between ML and Complexity Theory
Proving that the \(\mathrm{VC}\)-dimension, the measure of a finite dataset's complexity, is \(\Sigma_3^\mathrm P\)-complete, and can therefore be computed by counting.
Musings on Krapchenko's Formal Complexity
Showing that the space complexity of the parity function, \(\mathrm L_n(\bigoplus_n)\), is quadratic in the number of its leaves, \(n\).
Spectre and Meltdown Exploits
Exploiting buffer overflows to execute code on remote machines and accessing the root kernel of an actual Intel processor.
Permutations to Engineer Prison Breaks
The role of cyclic and symmetric groups in making choices during extreme (hypothetical) life or death situations.