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Dr TC/Tacey O'Neil

a photo of me at the bar wotever cabaret held in the royal vauxhall tavern in august 2021

Profile summary

Web links

Professional biography

I have worked at The Open University since 1999, intially as a lecturer in analysis and, since 2007, as a senior lecturer in analysis.

From 2010 to 2014 I was Head of the (then) Department of Mathematics and Statistics.

My name is Tacey but I'm also often called by my initials "TC" (TeeCee). I'm non-binary and I use she/they/them pronouns.


Research interests

I'm a real analyst with a particular interest in geometric measure theory and fractals. In particular, the structure of sets and measures in Euclidean spaces, and the relationship with classical problems in Analysis.

In my teaching scholarship, I'm interested in improving student mathematical resilience and module improvement. Recently my main focus has been on whether showing “mathematics being done ‘live’” (with the potential for errors) helps students change from a fixed to a growth mindset. Presentations and posters have been given at eSTEeM and OU teaching conferences.

Teaching interests

I am module chair of the third level pure mathematics module, M303, Further Pure Mathematics, and deputy chair of the dissertation module, M840, and the module on Fractal Geometry, M835, both of which are part of our MSc in Mathematics. I am also a member of the module team for the level 1 module MST125.

Research groups

NameTypeParent Unit
Pure Maths: Analysis & Geometry Research GroupGroupFaculty of Mathematics, Computing and Technology


Measuring Anisotropy in Planar Sets (2018-06-30)
O'Neil, Toby C.
Real Analysis Exchange, 43(1) (pp. 51-56)

Points of middle density in the real line (2012)
Csörnyei, Marianna; Grahl, Jack and O'Neil, Toby C.
Real Analysis Exchange, 37(2) (pp. 243-248)

Universal singular sets in the calculus of variations (2008-12)
Csörnyei, Marianna; Kirchheim, Bernd; O'Neil, Toby; Preiss, David and Winter, Steffen
Archive for Rational Mechanics and Analysis, 190(3) (pp. 371-424)

The Hausdorff dimension of the visible sets of planar continua (2007-11)
O'Neil, Toby
Transactions of the American Mathematical Society, 359(11) (pp. 5141-5170)

The Dimension of visible sets (2004-06)
O'Neil, Toby
Real Analysis Exchange, 30(1) (p 412)

Visible parts and dimensions (2003-05)
Järvenpää, Esa; Järvenpää, Maarit; MacManus, Paul and O'Neil, Toby C.
Nonlinearity, 16(3) (pp. 803-818)

The composition of two derivatives has a fixed point (2001-02)
Csörnyei, Marianna; O'Neil, Toby and Preiss, David
Real Analysis Exchange, 26(2) (pp. 749-760)

N-fold sums of Cantor sets (2000)
Hare, Kathryn and O'Neil, Toby
Mathematika, 47(1-2) (pp. 243-250)