Mathematics
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On the g2number of various classes of spheres and manifolds
For a $(d1)$dimensional simplicial complex $\Delta$, we let $f_i=f_i(\Delta)$ be the number of $i$dimensional faces of $\Delta$ for $1\leq i\leq d1$. One classic problem in geometric combinatorics is the following: ... 
Structure and complexity in nonconvex and nonsmooth optimization
Complexity theory drives much of modern optimization, allowing a fair comparison between competing numerical methods. The subject broadly seeks to both develop efficient algorithms and establish limitations on efficiencies ... 
The geometry of uniform measures
Uniform measures have played a fundamental role in geometric measure theory since they naturally appear as tangent objects. They were first studied in the groundbreaking work of Preiss where he proved that a Radon measure ... 
Spectral analysis in bipartite biregular graphs and community detection
This thesis concerns to spectral gap of random regular graphs and consists of two main con tributions. First, we prove that almost all bipartite biregular graphs are almost Ramanujan by providing a tight upper bound for ... 
Strichartz estimates for the wave equation on Riemannian manifolds of bounded curvature
Wave packet methods have proven to be a useful tool for the study of dispersive effects of the wave equation with coefficients of limited differentiability. In this thesis, we use scaled wave packet methods to prove ... 
Bin packing, number balancing, and rescaling linear programs
This thesis deals with several important algorithmic questions using techniques from diverse areas including discrepancy theory, machine learning and lattice theory. In Chapter 2, we construct an improved approximation ... 
Nonlocal operators, jump diffusions and FeynmanKac tranforms
Nonlocal operators are analytically defined by integrals over the whole space, hence hard to study certain properties. This thesis studies inverse local times at $0$ of onedimensional reflected diffusions on $[0, ... 
Novel uses of the Mallows model in coloring and matching
A natural model of a highly ordered random ranking is the Mallows model. Disorder is measured by the number of inversions; these are pairs of elements whose order is reversed. The Mallows model assigns to each ranking of ... 
Algorithms in Discrepancy Theory and Lattices
This thesis deals with algorithmic problems in discrepancy theory and lattices, and is based on two projects I worked on while at the University of Washington in Seattle. A brief overview is provided in Chapter 1 (Introduction). ... 
Bispectral Operator Algebras
This dissertation is an amalgamation of various results on the structure of bispectral differential operator algebras, ie. algebras of differential operators with possibly noncommutative coefficients in a variable $x$ ... 
A Survey of Tverberg Type Problems
Tverberg's theorem, which celebrates its fiftieth anniversary this year, is a central result in the fields of discrete geometry and topological combinatorics. Proved in 1966, it was a major step in solving questions whether, ... 
Cornered Asymptotically Hyperbolic Metrics
This thesis considers asymptotically hyperbolic manifolds that have a finite boundary in addition to the usual infinite boundary – cornered asymptotically hyperbolic manifolds. A theorem of CartanHadamard type near infinity ... 
Problems in Algebraic Vision
This thesis studies several fundamental mathematical problems that arise from computer vision using techniques in algebraic geometry and optimization. Chapters 2 and 3 consider the fundamental question of the existence of ... 
On fvectors of polytopes and matroids
The fvector of a simplicial complex is a fundamental invariant that counts the number of faces in each dimension. A natural question in the theory of simplicial complexes is to understand the relationship between the ... 
Some Inverse Problems in Analysis and Geometry
The aim of a typical inverse problem is to recover the interior properties of a medium by making measurements only on the boundary. These types of problems are motivated by geophysics, medical imaging and quantum mechanics ... 
On TSemisimplicity of Iwasawa Modules and Some Computations with Z3Extensions
For certain Zpextensions of abelian number fields, we study the Iwasawa module associated to the ideal class groups. We show that generic Zpextensions of abelian number fields are Tsemisimple. We also construct the ... 
Formal group laws and hypergraph colorings
This thesis demonstrates a connection between formal group laws and chromatic symmetric functions of hypergraphs, two seemingly unrelated topics in the theory of symmetric functions. A formal group law is a symmetric ... 
On the Geometry of Rectifiable Sets with Carleson and Poincaretype inequlaities
A central question in geometric measure theory is whether geometric properties of a set translate into analytical ones. In 1960, E. R. Reifenberg proved that if an $n$dimensional subset $M$ of $\mathbb{R}^{n+d}$ is well ... 
Boundary Harnack Principle for StableLike Processes
We establish the boundary Harnack principle for certain classes of symmetric stablelike processes in $\mathbf{R}^d$ on arbitrary open sets as well as censored stablelike processes on $\mathcal{C}^{1,1}$domains. Using ... 
Random recursion
We study the limiting behavior of three stochastic processes. Two are interacting particle systems, the frog model and coalescing random walk. We work out transience and recurrence properties on various graphs. The last ...