Update README.md

README.md

@@ -23,7 +23,7 @@ elliptic, convection-diffusion type of partial-differential equation
 ```
 
 The solution to this PDE is the value function $`V`$. In stationarity, the free boundary
-$`\partial \Omega`$ is the threshold on the vector state $`x_{\text{\tiny H}}`$ which 
+$`\partial \Omega`$ is the threshold on the state vector $`x_{\text{\tiny H}}`$ of a linear reset system, which 
 defines the optimal sampling scheme. The current implementation handles second-order systems.
 For more details, we refer to our [article](cdc2017_paper.pdf).