HIGHER-DIMENSIONAL SHRINKING TARGET PROBLEM FOR BETA DYNAMICAL SYSTEMS

 We consider the two-dimensional shrinking target problem in beta dynamical systems (for general 
 
 
 
$\beta>1$

 
 ) with general errors of approximation. Let 
 
 
 
$f, g$

 
  be two positive continuous functions. For any 
 
 
 
$x_0,y_0\in [0,1]$

 
 , define the shrinking target set 
 
 
 
$$ \begin{align*}E(T_\beta, f,g):=\left\{(x,y)\in [0,1]^2: \begin{array}{@{}ll@{}} \lvert T_{\beta}^{n}x-x_{0}\rvert <e^{-S_nf(x)}\\[1ex] \lvert T_{\beta}^{n}y-y_{0}\rvert < e^{-S_ng(y)} \end{array} \ {\text{for infinitely many}} \ n\in \mathbb N \right\}, \end{align*} $$

 
 
 where 
 
 
 
$S_nf(x)=\sum _{j=0}^{n-1}f(T_\beta ^jx)$

 
  is the Birkhoff sum. We calculate the Hausdorff dimension of this set and prove that it is the solution to some pressure function. This represents the first result of this kind for the higher-dimensional beta dynamical systems.