發送短信 : Boundary value problem of the operator ⊕<sup>k</sup>related to the biharmonic operator and the diamond operator

 _____     _    _    __   _      ___      _  __  
|  __ \\  | || | || | || | ||   / _ \\   | |/ // 
| |  \ || | || | || | '--' ||  | / \ ||  | ' //  
| |__/ || | \\_/ || | .--. ||  | \_/ ||  | . \\  
|_____//   \____//  |_|| |_||   \___//   |_|\_\\ 
 -----`     `---`   `-`  `-`    `---`    `-` --`