http://arxiv.org/pdf/math/0611889v4.pdf (page 13)

In the above paper by Danny Calegari he says that the result $\text{scl}(g) \geq 1/2$ (i.e. a stable commutator length $\text{scl}(g) := \displaystyle{\lim_n}\ cl(g^n) / n$, where $\text{cl}(g)$ is the smallest $k$ such that $g$ is a product of $k$ commutators) follows (apart from the Howie-Duncan result) from the paper by Comerford-Edmunds.

"Products of commutators and products of squares in a free group" by Leo P. Comerford , Jr. , Charles C. Edmunds, 1994.

Although I am familiar with that paper, I do not immediately see how that result follows from the description of solutions of quadratic equations described in Comerford&Edmunds.

Here is a reference to the paper:

http://citeseerx.ist.psu.edu/viewdoc/summary?doi=10.1.1.233.9038

Could anyone clarify the link between the two results?

thanks!