After receiving my Ph.D., I then became self-employed and as a job-seeker. So I use my spare time to continue doing research in the field of my dissertation on my own and came up with some results that I view as an extension of the results which are not included in my thesis nor published anywhere. Here is my question
Is it ethical to submit these results as a sole-author paper and perhaps list my advisor name in acknowledgment section for thanking him to bring me into the field ? or should I contact my advisor and asking his permission for publication?
p.s. I do theoretical research, so there are no experiment issues or budget concerns.