As Jeff Atwood answers in "Does Stack Overflow have a sitemap?", Stack Overflow has a Sitemap, but they protect it.
My question is about Stack Overflow Sitemap implementation when a question is "deleted" or "updated".
Does Stack Overflow generate a new record of this question URL in the current sitemap file then submit/ping again?
Or change the last modified date in the question URL record in the old sitemap file then submit/ping again?
Does Stack Overflow delete the question URL record of this question from sitemap file?
Or how does it inform search engines about a deleted question to remove it from the index?