
Joel Friedman's OnLine Publications
(This page is currently under construction papers are being added. Let
me know if there are particular papers you'd like me to add.)
If a paper has figures, these figures will not be visible with the
"dvi" version of the paper.
Here
is a remarkable and much shorter
proof of the Hanna Neumann Conjecture,
which simplifies, generalizes, and clarifies aspects of
my sheaf theoretic proof,
by Warren Dicks, written entirely in the language of skew group rings.

Linear Algebra and
the Hanna Neumann Conjecture,
July 28, 2011.

Sheaves on Graphs, Their Homological Invariants,
and a Proof of the Hanna Neumann Conjecture,
May 30, 2011. Note: this paper is a merged version (with redundancies
eliminated) of the two papers listed just below.

Sheaves on Graphs and a Proof of the Hanna Neumann Conjecture,
April 30, 2011.

Sheaves on Graphs and Their Homological Invariants,
April 13, 2011.

The nonbacktracking spectrum of the universal cover of a graph,
with Omer Angel and Shlomo Hoory,
last modified November 20, 2007.

Cohomology in Grothendieck Topologies and Lower Bounds in Boolean
Complexity II: A Simple Example (8 pages),
last modified March 30, 2006.

Cohomology in Grothendieck Topologies and Lower Bounds in Boolean
Complexity (70 pages),
last modified December 2, 2005.

A Proof of Alon's Second Eigenvalue Conjecture (118 pages),
last modified (third revision) May 3, 2004.
Accepted to the Memoirs of the A.M.S.

Generalized AlonBoppana Theorems and ErrorCorrecting Codes,
with JeanPierre Tillich, last modified May 27, 2002.

Wave Equations for Graphs and The Edgebased Laplacian,
with JeanPierre Tillich, last modified May 24, 2002, accepted to the
Pacific Journal of Mathematics.

Relative Expanders or Weakly Relatively Ramanujan Graphs,
last modified April 8, 2002,
Duke Mathematical Journal

Recognizing more unsatisfiable random 3SAT
instances efficiently,
with Andreas Goerdt, last modified January 26, 2001.

Laplacian Eigenvalues and Distances Between Subsets of a Manifold,
with JeanPierre Tillich, last modified November 22, 2000.
 On Cayley Graphs on the Symmetric
Group Generated by Tranpositions, last modified March 27, 2000.
 The Action of a Few
Permutations on rtuples is Quickly Transitive, with Antoine Joux,
Yuval Roichman, Jacques Stern, and JeanPierre Tillich,
last modified January 23,
1998.
 Computing Betti Numbers via
Combinatorial Laplacians, last modified June 4, 1997.
 On the Betti Numbers of Chessboard
Complexes, with Phil Hanlon, last modified May 14, 1997.

Relative Expansion and an Extremal Degree Two Cover of the Boolean Cube,
last modified 19935.

Some Geometric Aspects of Graphs and their Eigenfunctions,
last modified October 26, 1992 (or earlier?).

On the Bit Extraction Problem, last modified August 12, 1992.

A Note on Matrix Rigidity, last modified October 25, 1991.

The Spectra of Infinite Hypertrees, last modified September 13, 1990.

On the Second Eigenvalue of Hypergraphs, last modified November 11, 1989.

Some Graphs with Small Second Eigenvalue, last modified October 12, 1989.

A Deterministic View of Random
Sampling and its Use in Geometry, with Bernard Chazelle, last modified ???
 On the Second Eigenvalue and Random Walks
in Random dRegular Graphs, last modified May 22, 1989.
 On the Roadmap Coloring Problem, last
modified January 1989.
 A Density Theorem for
Purely Iterative Zero Finding Methods, last
modified January 1989.
 On the Convergence of
Newton's Method, last
modified September 1988.
 Random Polynomials and
Approximate Zeros of Newton's Method, last
modified November 1987.
