English
If A is finite and doubling is below 3/2 of |A|, then A⁻¹·A is a subgroup of G.
Русский
Если A — конечное множество, чья размерность тройной суммы меньше 3/2 от |A|, то A⁻¹·A является подгруппой G.
LaTeX
$$$\text{InvMulSubgroup}(A,h)\;\text{car} = A^{-1} A$ и более:
\text{carrier} = A^{-1} A \,\wedge\; \text{Subgroup}$$$
Lean4
/-- A non-empty set with no doubling is the right translate of its stabilizer. -/
@[to_additive /-- A non-empty set with no doubling is the right translate of its stabilizer. -/
]
theorem op_smul_stabilizer_of_no_doubling (hA : #(A * A) ≤ #A) (ha : a ∈ A) : (stabilizer G A : Set G) <• a = A :=
(smul_stabilizer_of_no_doubling_aux hA ha).2