ON THE GREATEST FIXED-POINT OF A SET FUNCTOR

被引:37
作者
ADAMEK, J [1 ]
KOUBEK, V [1 ]
机构
[1] CHARLES UNIV,FAC MATH & PHYS,PRAGUE 1,CZECH REPUBLIC
关键词
D O I
10.1016/0304-3975(95)00011-K
中图分类号
TP301 [理论、方法];
学科分类号
081202 ;
摘要
The greatest fixed point of a set functor is proved to be (a) a metric completion and (b) a CPO-completion of finite iterations. For each (possibly infinitary) signature Sigma the terminal C-coalgebra is thus proved to be the coalgebra of all C-labelled trees; this is the completion of the set of all such trees of finite depth. A set functor is presented which has a fixed point but does not have a greatest fixed point. A sufficient condition for the existence of a greatest fixed point is proved: the existence of two fixed points of successor cardinalities.
引用
收藏
页码:57 / 75
页数:19
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