29 citations · 203 across the 38 of their papers we have counts for
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math.CO2010★ 13 cited
Matrices with restricted entries and q-analogues of permutations
Joel Brewster Lewis, Ricky Ini Liu, Alejandro H. Morales +3
We study the functions that count matrices of given rank over a finite field with specified positions equal to zero. We show that these matrices are -analogues of permutations w…
math.CO2010★ 1 cited
Baron Munchhausen Redeems Himself: Bounds for a Coin-Weighing Puzzle
Tanya Khovanova, Joel Brewster Lewis
We investigate a coin-weighing puzzle that appeared in the Moscow Math Olympiad in 1991. We generalize the puzzle by varying the number of participating coins, and deduce an upper…
math.CO2010★ 13 cited
Generating trees and pattern avoidance in alternating permutations
Joel Brewster Lewis
We extend earlier work of the same author to enumerate alternating permutations avoiding the permutation pattern 2143. We use a generating tree approach to construct a recursive bi…