Products of involutory matrices over rings

Let αε{lunate}GL_n A be a matrix over a commutative ring A with 1 such that (det α)² = 1. If α is cyclic, it can be written as a product of at most three involutions. When A satisfies the first Bass stable range condition, then α can be written as a product of at most five involutions. If in addition either n ≤ 3 or n = 4 and det α = -1, then α can be written as a product of at most four involutions. When A is a Dedekind ring of arithmetic type, the number of involutions needed to express α is uniformly bounded for any n ≥ 3. When A = C[x] the number of involutions is unbounded for any n ≥ 2.