(This is a cross-post from MathSE, as someone remarked that the question would be more appropriate on MO)


[Fiore and Leinster](http://arxiv.org/pdf/math/0508617v2.pdf) have proved that if $\mathcal{A}$ is a monoidal category freely generated by one object $A$ and an isomorphism $\alpha: A \otimes A \to A$, then for every object $X \in \mathcal{A}, Aut(X)$ is isomorphic to the Thompson group $F$.


My question is the following: if we assume instead that $\alpha: A \otimes A \to A$ is not necessarily an isomorphism, and that there exist a morphism $\beta: A \to A \otimes A$ such that $\alpha \circ \beta = id$, is the result of Fiore and Leinster still true ? 


I have a feeling we at least have $F \subset Aut(X)$. Loosely speaking, my approach is that since every element of $F$ can be represented as a pair $(R,S)$ of forests, we can always represent $R$ by a suitable composition of $\beta$ maps, then $S$ by a composition of $\alpha$ maps, the identity $\alpha \circ \beta = id$ ensuring that every facing caret gets cancelled to form a reduced forest diagram, i.e a unique element of $F$.



Thompson's group F and monoidal categories
**Edit** I noticed that in Fiore-Leinster preliminate the condition (free monoidal category of an isomorphism $ \alpha: A \otimes A \to A $) is different from what is written in the preliminary question, so I reworked my answer substantially.


In a Monoidal category $\mathcal{C}$ consider (a non empty) class of sections of the type $\beta: A\to A\otimes A$ and let $\Sigma$ its tensor product closure (finite tensor products of some morphisms of type $ \beta $ of the choose class and some identities).


From the article "Note on monoidal localizations " by B. Day ([link text](http://journals.cambridge.org/action/displayAbstract?fromPage=online&aid=4865952)) the category of fraction $\mathcal{C}\_\Sigma$
is (naturally) a monoidal category.


let $P: \mathcal{C}\to \mathcal{C}\_\Sigma$ the natural functor.


The elements of $\Sigma$ are all monomorphisms (are sections) , and if $\Sigma$ admits a calculus of left fractions the canonical functors $P$ is faithful (see "Categories" H Shubert, 12.9.6(a), p.261). THen $\mathcal{C}$-$Aut(X)$ is a subgroup of $\mathcal{C}\_\Sigma$-$Aut(X)$ (because $P$ is faithful).


Now consider the Monoidal category $[A, \alpha, \beta]$ free on (the condition):


"one object $A$ and on two morphisms $\alpha: A\otimes A\to A$, $\beta: A\to A\otimes A$, with $\alpha\circ \beta=1\_A$". 


This category has the following universal property: for any monoidal categories $\mathcal{C}$ with choose morphisms $a: X\otimes X\to X,\ b: X\to X\otimes X$ with $a\circ b=1\_X$ there exists a unique strict monoidal functor $F\_{a,b}: [A, \alpha, \beta]\to \mathcal{C}$ with $F(\alpha)=a,\ F(\beta)=b$.


Now in $[A, \alpha, \beta]$ consider the tensor closure $\Sigma$ of the section $\beta$,


and let $P:[A, \alpha, \beta]\to [A, \alpha, \beta]\_\Sigma$ the category of fractions.


the category $[A, \alpha, \beta]\_\Sigma $ has the universal property of the monoidal category on one isomorphisms


$\beta: A\to A\otimes A$ as in the FIore-Leinster article, then 
$F\cong [A, \alpha, \beta]\_\Sigma$-$Aut(A)$. 


Now, **IF** $\Sigma$ admit a calculus of left fraction then $P$ is faithful and 
$[A, \alpha, \beta]$-$Aut(A)$ is isomorphic to a subgroup of $F$.


P.S. I seems that $\Sigma$ admit a calculus of left fraction, but I have not checked it in detail 


