Hello! I’m a fourth year mathematics Ph.D. student and NSF graduate fellow at the University of Pennsylvania, advised by Mona Merling. I’m generally interested in algebraic topology and homotopy theory, and I also have an interest in mathematical visualization and communication. I believe that math can be accessible and enjoyable for everyone. Here is my CV.

Pronouns: she/her or they/them

Email: callem “at” sas “dot” upenn “dot” edu


  • My name is pronounced “mack-SEEN eh-LEH-na CAH-shay.” I grew up in San Diego, CA, and I attended the Waldorf School of San Diego. My high school education inspired me to do a lot of art, music, and performance. (You can check out some of my art and stuff here.)
  • I got a B.A. in math in 2020 from Reed College in Portland, OR. I started out as a Philosophy major, but switched to Math at the end of my second year. I worked closely with Kyle Ormsby and Angélica Osorno, and they both got me into algebraic topology. I also worked with Paul Hovda in the Philosophy department, thinking about stuff like mathematical structuralism. I was featured on What is a Reedie? where I talk a bit about myself, my undergraduate thesis, and my Reed College experience. Read my full responses here.
  • My REU experience with Corey Dunn convinced me to pursue math graduate school. I started my Ph.D. at the University of Pennsylvania in the Fall of 2020. I passed my oral exam in Spring 2022 (here’s the syllabus and my master’s thesis).
  • In summer 2023, I was an AAAS Mass Media Fellow at The Conversation US. Learn more about what I worked on here.

Upcoming Travel and Conferences

  • November-December 2023: Spaces of Manifolds: Algebraic and Geometric Approaches BIRS Workshop; Banff, Alberta (Canada).
  • January 2024: JMM; San Francisco, CA.
  • July 2024: Scissors congruences, algebraic K-theory and Steinberg modules AIM Workshop;  Caltech, CA.
  • November 2023: Loyola University TACO seminar; Chicago, IL.
  • November 2023: Michigan State University RTG seminar; MSU, MI.
  • September 2023: Binghamton University Geometry and Topology seminar; SUNY Binghamton, NY.
  • July 2023: Scissors Congruence, Algebraic K-theory, and Trace Methods summer school; Indiana University, IN.
  • June 2023: Mass Media Fellow orientation; Washington D.C.
  • June 2023: Talbot Workshop; McGrath, MN.
  • May 2023: UCLA algebraic topology seminar; Los Angeles, CA.
  • May 2023: UCSD topology seminar; San Diego, CA.
  • April 2023: Midwest Topology Seminar; Purdue University, IN.
  • April 2023: Purdue University topology seminar; Lafayette, IN.
  • April 2023: Mid-Atlantic Topology Conference; University of Pennsylvania, PA.
  • April 2023: University of Rochester topology seminar; Rochester, NY.
  • March 2023: Math PATCH Seminar; Bryn Mawr College, PA.
  • February 2023: University of Virginia topology seminar; Charlottesville, VA.
  • January 2023: Spring Opportunities Workshop; Institute for Advanced Study, NJ.
  • November 2022: Binghamton University Graduate Combinatorics, Algebra, and Topology (BUGCAT) Conference; SUNY Binghamton, NY.
  • September 2022: Floer Homotopy Theory Connections Workshop and Introductory Workshop; MSRI, CA.
  • August 2022: RTG Collaborative Workshop in Homotopy Theory; Good Place Farms, VA.
  • July 2022: Séminaire de Mathématiques Supérieures: Floer Homotopy Theory; University of British Columbia, Vancouver (Canada).
  • June 2022: Talbot Workshop; New Lebanon, NY.
  • May-June 2022: Algebraic Structures in Topology; San Juan, PR.
  • May 2022: Graduate Student Conference in Algebra, Geometry, and Topology; Temple University, PA.
  • May 2022: Cornell Topology Festival; Cornell University, NY.
  • April 2022: Math PATCH Seminar; Temple University, PA.
  • February 2022: MATH for all in Nola; online.
  • October 2021: Math PATCH Seminar; Bryn Mawr College, PA.
  • July 2021: PCMI's "Illustrating Mathematics" Graduate Summer School; online.
  • Summer 2021: Algebraic Topology Bridge Summer Workshop; online.
  • April 2021: Underrepresented Students in Algebra and Topology Research Symposium (USTARS); online.
  • April 2021: Graduate Student Topology and Geometry Conference (GSTGC); online.
  • November 2020: Binghamton University Graduate Conference in Algebra and Topology (BUGCAT); online.
  • September 2020: Cascade Topology seminar; online.
  • Summer 2020: Algebraic Topology Bridge Summer Workshop; online.
  • Summer 2020: Graduates Reminisce Online on Topology seminar (GROOT); online.
  • January 2020: Nebraska Conference for Undergraduate Women in Mathematics (NCUWM); University of Nebraska-Lincoln, NE.
  • May 2019: Women and Mathematics (WAM); Institute for Advanced Study, NJ.
  • Summer 2019: Collaborative Mathematics Research Group (CMRG); Reed College,  OR.
  • January 2019: Joint Mathematics Meetings (JMM); Baltimore, MD.
  • November 2018: Undergraduate Mathematics Symposium (UMS); University of Illinois at Chicago, IL.
  • November 2018: Northwest Undergraduate Mathematics Symposium (NUMS); Willamette University, OR.
  • Summer 2018: NSF REU program; California State University, San Bernardino, CA.