*1:See also https://sumita-m.hatenadiary.com/entry/20070627/1182948456 https://sumita-m.hatenadiary.com/entry/20140806/1407294791 https://sumita-m.hatenadiary.com/entry/20140808/1407472686 https://sumita-m.hatenadiary.com/entry/20160408/1460082660 https://sumita-m.hatenadiary.com/entry/20160409/1460210680 https://sumita-m.hatenadiary.com/entry/2019/06/20/002830 https://sumita-m.hatenadiary.com/entry/2021/12/07/082948