Matveev–Jaco–Rubinstein conjecture on the complexity of lens spaces

Let $L(n,1)$ denote the lens space with parameters $n$ and $1$, and let $c(M)$ be the pseudo-simplicial complexity of a closed $3$-manifold $M$, namely the minimal number of $3$-simplices in a pseudo-simplicial triangulation of $M$.

Matveev–Jaco–Rubinstein conjecture. For $n>3$,

$$c(L(n,1))=n-3.$$

This is the $q=1$ case of the broader conjecture that $c(L(p,q))=S(p,q)-3$, where $S(p,q)$ is the sum of the partial quotients in the continued-fraction expansion of $p/q$. The source presents the assertion as a conjecture attributed independently to Matveev and to Jaco and Rubinstein; its resolution status is not specified here.