BRENT CODY

Associate Professor
Department of Mathematics
    and Applied Mathematics
Virginia Commonwealth University
bmcody@vcu.edu



Welcome to my website!

Research Overview

My main line of research is in set theory and involves large cardinals. I've done work on combinatorial principles and forcing constructions related to the large cardinal properties of Ramseyness, ineffability and indescribability. I've also worked on strong properties of successor cardinals that hold after collapsing large cardinals and on preserving large cardinals through Easton-support forcing iterations.

I also have an emerging interest in problems involving graph theory, finite combinatorics, discrete optimization and connections with music via maximal evenness and Euclidean rhythms (see [20] and [22] below).

Papers

  1. The \(k\)-general \(d\)-position problem for graphs. (with Garrett Moore) Submitted. (pdf)
  2. Maximal evenness in graphs. (with Neal Bushaw and Chris Leffler) Submitted. (pdf)
  3. Large cardinal ideals. Accepted chapter for Research Trends in Contemporary Logic, 49 pages. (pdf)
  4. The Music and Mathematics of Maximally Even Sets. (with Neal Bushaw, Luke Freeman and Tobias Whitaker) Proceedings of Bridges 2024: Mathematics, Art, Music, Architecture, Culture: pp. 61-68. (pdf)
  5. Two-cardinal derived topologies, indescribability and Ramseyness. (with Chris Lambie-Hanson and Jing Zhang) Accepted at Journal of Symbolic Logic. (pdf)
  6. Two-cardinal ideal operators and indescribability. (with Philip White) Annals of Pure and Applied Logic, 175 (8): Paper No. 103463, 17 pp., 2024. (pdf)
  7. Higher indescribability and derived topologies. Journal of Mathematical Logic 24 (1): Paper No. 2350001, 48 pp., 2024. (pdf)
  8. Sparse analytic systems. (with Sean Cox and Kayla Lee) Forum of Mathematics, Sigma, Paper No. e58, 9 pp., 2023. (pdf)
  9. Ideal operators and higher indescribability. (with Peter Holy) Journal of Symbolic Logic, 88 (2):835-873, 2023. (pdf)
  10. Forcing a \(\square(\kappa)\)-like principle to hold at a weakly compact cardinal. (with Victoria Gitman and Chris Lambie-Hanson) Annals of Pure and Applied Logic, 172 (7):102960, 26 pp., 2021. (pdf)
  11. A refinement of the Ramsey hierarchy via indescribability. Journal of Symbolic Logic, 85 (2):773-808, 2020. (pdf)
  12. Characterizations of the weakly compact ideal on \(P_\kappa\lambda\). Annals of Pure and Applied Logic, 171 (6):23 pages, 2020. (pdf)
  13. The weakly compact reflection principle need not imply a high order of weak compactness. (with Hiroshi Sakai) Archive for Mathematical Logic, 59 (1):179-196, 2020. (pdf)
  14. Adding a non-reflecting weakly compact set. Notre Dame Journal of Formal Logic, 60 (3):503-521, 2019. (pdf)
  15. Rigid ideals. (with Monroe Eskew) Israel Journal of Mathematics, 224 (1):343-366, 2018. (pdf)
  16. Indestructibility of generically strong cardinals. (with Sean Cox) Fundamenta Mathematicae, 232 (2):131-149, 2016. (pdf)
  17. The least weakly compact cardinal can be unfoldable, weakly measurable and nearly \(\theta\)-supercompact. (with Moti Gitik, Joel David Hamkins, and Jason Schanker) Archive for Mathematical Logic, 54 (5-6):491-510, 2015. (pdf)
  18. Easton's theorem for Ramsey and strongly Ramsey cardinals. (with Victoria Gitman) Annals of Pure and Applied Logic, 166 (9):934-952, 2015. (pdf)
  19. Easton functions and supercompactness. (with Sy Friedman and Radek Honzik) Fundamenta Mathematicae, 226 (3):279-296, 2014. (pdf)
  20. On Supercompactness and the continuum function. (with Menachem Magidor) Annals of Pure and Applied Logic, 165 (2):620-630, 2014. (pdf)
  21. Easton's Theorem in the presence of Woodin cardinals, Archive for Mathematical Logic, 52 (5-6):569-591, 2013. (pdf)
  22. Consecutive singular cardinals and the continuum function. (with A. W. Apter) Notre Dame Journal of Formal Logic, 54 (2):125-136, 2013. (pdf)
  23. The failure of GCH at a degree of supercompactness. Mathematical Logic Quarterly, 58 (1-2):83-94, 2012. (pdf)

Teaching

Some Diagrams + Audio

Bomba is one of the oldest Puerto Rican musical traditions of African origin. In the following diagram taken from [20] (joint work with Bushaw, Freeman and Whitaker), we see some popular bomba rhythms that correspond to minimal energy subsets of Möbius ladders.

The bomba yubá is shown in (a); it is the unique minimal energy subset of size four of the Möbius ladder on six vertices. Listen to the bomba yubá here:

The bomba sicá is shown in (b); it is the unique minimal energy subset of size four of the Möbius ladder on eight vertices. Listen to the bomba sicá here:


 

 
In the following diagram taken from [20] (joint work with Bushaw, Freeman and Whitaker), some heptatonic (i.e. seven note) scales are arranged in order of increasing energy from left to right. You can listen to the scales by clicking on the links below.


Major scale

Melodic Minor

Major Neapolitan

Harmonic Minor

Hungarian Major

Minor Neapolitan

Gamanashrama

Marwa

Double Harmonic

Todi

Jalavarnam

Jhalavarali

 
In the next diagram, taken from [20] (joint work with Bushaw, Freeman and Whitaker), triads are arranged in order of increasing energy from left to right. You can listen to the triads using the links below.

Augmented Triad

Minor Triad

Diminished Triad

Sus. 4 Triad

Italian Augmented 6th Chord

Tritone Add Minor 2nd


Local minimizers can be found by gradient descent

Gradient descent with 28 vertices on \(C_{64}\).
Gradient descent with 30 vertices on \(C_{20}\Box C_{20}\).

Minimizers on a 4-cube and toroidal graphs

4-cube
1 x 8 torus
2 x 8 torus
4 x 4 torus
5 x 5 torus