关键词：严格因果分量；反馈配置；定点理论；函数
摘 要：We ask whether strictly causal components form well de ned systems when arranged in feedback con gurations. The standard interpretation for such con gurations induces a xed-point constraint on the function modelling the component involved. We de ne strictly causal functions formally, and show that the corresponding xed-point problem does not always have a well de ned solution. We examine the relationship between these functions and the functions that are strictly contracting with respect to a generalized distance function on signals, and argue that these strictly contracting functions are actually the functions that one ought to be interested in. We prove a constructive xed-point theorem for these functions, introduce a corresponding induction principle, and study the related convergence process.