From a Toronto Star video pictured here on April 1 three years ago:
The three connected cubes are labeled "Harmonic Analysis," 'Number Theory,"
and "Geometry."
Related cultural commentary from a review of the recent film "Justice League" —
"Now all they need is to resurrect Superman (Henry Cavill),
stop Steppenwolf from reuniting his three Mother Cubes
(sure, whatever) and wrap things up in under two cinematic
hours (God bless)."
The nineteenth-century German mathematician Felix Christian Klein
as Steppenwolf —
Volume I of a treatise by Klein is subtitled
"Arithmetic, Algebra, Analysis." This covers
two of the above three Toronto Star cubes.
Klein's Volume II is subtitled "Geometry."
An excerpt from that volume —
Further cultural commentary: "Glitch" in this journal.