fix typo issue

paper/paper.md

@@ -52,11 +52,9 @@ where $c(t,x,y)$ is the local pheromone concentration, $\mathbf{K}$ is a diffusi
 ## BI-DA to solve the inverse problem
 
 We define BI-DA with the following optimization problem: find the optimal quantity of pheromone emitted in time and space $s_a(t,x,y)$ such that
-$
 \begin{equation}\label{eq: VDA-probleme-optimisation}
         s_a(x,y,t)=\underset{s(x,y,t)}{\mathop{\mathrm{argmin}}}\text{~}j(s)\text{ with } j(s)=j_{obs}(s)+j_{reg}(s)
 \end{equation}
-$
 where $j_{obs}$ is the observation loss and $j_{reg}$ is a regularization term. Namely
 $$j_{obs}(s)=\|m\left(c(s)\right)-m^{obs}\|_{\mathbf{R}^{-1}}^2$$
 where $c(s)$ is the concentration map obtained by solving the CTM \autoref{eq:2D pheromone propagation model} with second member $s$, $m^{obs}$ are noisy observations with covariance $\mathbf{R}$, and $c\mapsto m$ is an observation operator.