Enable us and become a hero by incorporating new entries and evaluating present types. Like a thanks, You can utilize this website devoid of ads when you finally achieve a specific score. 最简单的说法，即是在最原始的集合论。集合是把人们的直观的或思维中的某些确定的能够区分的对象汇合在一起，使之成为一个整体或称为单体，这一整体就是集合。 Here A' and B' are the list of accumulation points... https://bihlmayermedia-bilder.com/1-advent/