Testing LaTex

[Martin Paech]

$$R=\big(\underbrace{r_{1}, r_{2}, \dots, r_{g_{1}}}_{\varrho^{}_{1}\;\text{,}\;\;r'_{1}=r^{}_{g_{1}}}, \underbrace{r_{g_{1}+1}, r_{g_{1}+2}, \dots, r_{g_{2}}}_{\varrho^{}_{2}\;\text{,}\;\;r'_{2}=r^{}_{g_{2}}}, \dots, \underbrace{r_{g_{u-1}+1}, r_{g_{u-1}+2}, \dots, r_{g_{u}}}_{\varrho^{}_{u}\;\text{,}\;\;r'_{u}=r^{}_{g_{u}}}\big)$$