Y-N Sets and the Category of Y-N Sets
Xiaoshen Li, Xue-hai Yuan · 2009
In order to describe complicated concepts, the concept of Y-N set is introduced. Firstly, the operations on Y-N sets such as union, intersection, difference and complement of Y-N sets are presented. Secondly, the definitions of image and preimage of a Y-N set under a mapping are given and the properties of the image and preimage are discussed. Finally, a category YNSet of Y-N sets is established and it is proved that the category YNSet is a weak topos.