On Smithson’s fixed point theorem for order preserving multifunctions
指出Smithson(1971)保序多值函数不动点定理原始证明中的错误，给出新的简洁证明，并得到不动点集结构和单调比较静态的新结果。
Fixed point theorems are ubiquitous in economic research. Many studies cite Smithson (1971) “Fixed points of order preserving multifunctions,” yet the original proof contains errors. This note presents a new, concise proof and explains why Smithson’s argument is invalid. It also contains new results on the structure of the set of fixed points and monotone comparative statics.