PDF files of selected papers and preprints

In the below subheadings, you can find pdf files of some of my papers and preprints. While essentially have the same content as, they may be different in detail from the arXiv or published versions. For an updated version, you may look at the journal's version or email me.

I tried to put a paper in one subheading which is closest to its content, but it may also be close to other headings.

Addendum (13 August 2020): The new format of Google sites just puts all the files to Google Drive. So sorry you don't see the files any more, but if you like to have one paper, just write to me and I am happy to send a copy to you.