The Qijue 棋訣 (also 碁訣 or 棊訣) "Explanations to chess" is a short treatise on Chinese chess written by the Southern Song period 南宋 (1127-1279) master Liu Zhongfu 劉仲甫. Liu came from Qiantang 錢塘 (modern Hangzhou 杭州, Zhejiang), of whose life is not much known. Although Liu Zhongfu is known as a champion, there were also occasions when he was beaten, like demonstrated in the books Chunzhu jiwen 春渚紀聞 and Tieweishan congtan 鐵圍山叢談.
His book has four chapters, speaking on allocation (buzhi 布置), attack (qinling 侵凌), "battle" (yongzhan 用戰) and "conquest" (qushe 取舍). At the end of the book, the last chapter of Yan Tianzhang's 晏天章 book Qijing 棋經 is added, Lunqi zashuo 論棋雜說, to which Liu Zhongfu has added some comments.
The Qijue is included in the reprint series Mohai jinhu 墨海金壺 and Zhucong bielu 珠叢別錄, as well as in the encyclopedia Yongle dadian 永樂大典.
Source: Li Xueqin 李學勤, Lü Wenyu 呂文鬰 (1996). Siku da cidian 四庫大辭典, vol. 2, p. 1823. Changchun: Jilin daxue chubanshe.