盘覆盖问题：在一个2k×2k 个方格组成的棋盘中，恰有一个方格与其它方格不同，称该方格为一特殊方格，且称该棋盘为一特殊棋盘。在棋盘覆盖问题中，要用图示的4种不同形态的L型骨牌覆盖给定的特殊棋盘上除特殊方格以外的所有方格，且任何2个L型骨牌不得重叠覆盖。-Set cover problem: in a 2k × 2k grid consisting of a chessboard, just have a box with other boxes is different from that of the grid is a special box, and said the board is a special board. Coverage in the chessboard problems, the four kinds of icons to use different forms of L-type domino coverage given special chessboard except in special box outside the grid of all, and any two L-type domino coverage shall not overlap.