Difference sets are not multiplicatively closed
Discrete analysis (2016)
Cet article a éte moissonné depuis la source Scholastica
We prove that for any finite set A of real numbers its difference set D:=A-A has large product set and quotient set, namely, |DD|, |D/D| \gg |D|^{1+c}, where c>0 is an absolute constant. A similar result takes place in the prime field F_p for sufficiently small D. It gives, in particular, that multiplicative subgroups of size less than p^{4/5-\eps} cannot be represented in the form A-A for any A from F_p.
@article{DAS_2016_a2,
author = {Ilya D. Shkredov},
title = {Difference sets are not multiplicatively closed},
journal = {Discrete analysis},
year = {2016},
language = {en},
url = {http://geodesic.mathdoc.fr/item/DAS_2016_a2/}
}
Ilya D. Shkredov. Difference sets are not multiplicatively closed. Discrete analysis (2016). http://geodesic.mathdoc.fr/item/DAS_2016_a2/