在本篇論文中，我們主要研究某類傳染病模型的微分方程，其行波解的存
在且該行波解為monotonic。利用monotone iteration這個方法，結合我們所
建構的上解和下解，證明當存在最小的波速c* ，而且當波速高於最小波速
c* 時，行波解是存在的。

The purpose of this thesis is to investigate the existence of monotonic traveling
wave solutions for some epidemic models. Using the monotone iteration method,
combining with a pair of upper solution and lower solution, we show that there
exist a minimal wave speed c* such that if the wave speed is greater than c* ,
then there exist monotone traveling wave solutions.

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