Who is the XXX named after?
Chebyshev's sum inequality
In mathematics, Chebyshev's sum inequality, named after Pafnuty Chebyshev, states that if a_1 \geq a_2 \geq \cdots \geq a_n and b_1 \geq b_2 \geq \cdots \geq b_n, then (1\over n) \sum--(k=1)^n a_k \cdot b_k \geq \left((1\over n)\sum--(k=1)^n a_k\right)\left((1\over n)\sum--(k=1)^n b_k\right).
Pafnuty Chebyshev