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AC — Commutative Algebra
AG — Algebraic Geometry
AP — Analysis of PDEs
AT — Algebraic Topology
CA — Classical Analysis and ODEs
CO — Combinatorics
CT — Category Theory
CV — Complex Variables
DG — Differential Geometry
DS — Dynamical Systems
FA — Functional Analysis
GM — General Mathematics
GN — General Topology
GR — Group Theory
GT — Geometric Topology
HO — History and Overview
IT — Information Theory
KT — K-Theory and Homology
LO — Logic
MG — Metric Geometry
MP — Mathematical Physics
NA — Numerical Analysis
NT — Number Theory
OA — Operator Algebras
OC — Optimization and Control
PR — Probability
QA — Quantum Algebra
RA — Rings and Algebras
RT — Representation Theory
SG — Symplectic Geometry
SP — Spectral Theory
ST — Statistics Theory
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OP-00006
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Lehmer's totient problem
NT
·
Euler's totient function