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Giorgis Petridis works on growth estimates in additive combinatorics. His paper gives a short proof of Plünnecke inequalities and extensions to product sets in groups.^[ref]

The proof chooses a subset with a minimal expansion ratio and uses that choice to control further sums. This converts one small-growth hypothesis into bounds for iterated sum-and-difference sets. The noncommutative setting requires separate product-set arguments because the order of multiplication matters.^[ref]