You can click on "Account" at the top, and then "Personal Information" to change your username to your real name. (You can also enter your "real name," but this doesn't change what is shown by your posts, just what people see when they look at your profile).
]]>Also, people don't want to use bare last names; they want to include a title. This makes sense, I think, because a lot of the cases where people are using other people's names it's in a reply to a comment. This is directly addressing the person in question, and you wouldn't use a bare last name in conversation like that. And calling a person you're not familiar with "Dr. X" in a forum like this, where people's academic rank is not necessarily clear, is just asking for confusion. Every so often I get e-mails addressed to "Dr. Lugo" or "Professor Lugo", and I am still a grad student, so I find this amusing. (Although one e-mail addressed to "Professor Lugo" came from a search committee for a job, and one would hope they'd know I'm not a professor yet.)
]]>You are right in pointing out that I don't quite follow the rules outlined: e.g. with FC, I know that he prefers FC to his name, and so would use it. I think with the people I know personally, I have a reasonable sense of what they would prefer, and if they want me to do something else, they can just let me know.
]]>Most Chinese surnames have one syllable. There are exceptions though, but they are rare. The most common multisyllabic Chinese surname is probably Auyeung/Ouyang.
Most Chinese "first names" have two syllables. But there are many with one syllable, for example the basketball player Yao Ming (surname Yao, "first name" Ming). It is extremely rare to have more than two syllables in a "first name", but I know one person with three.
When encountering Chinese names on Mathoverflow, in the mathematical community, and in most of the contemporary western world, I think it should be usually safe to assume that the surname is at the end of the name. But there will always be some exceptions... like Yao Ming.
]]>It seems there are some corner cases in your rule: if you were replying to FC, would you use his first name? The concern here is that his profile is sufficiently anonymous so as to clearly be intentionally so, but many of us both know who FC really is, and would happily use his first name in most situations.
]]>I adopt the following policy: if a person includes a first name in their username, I address them with it. If they don't, and I don't know them personally, then I address them by their username, whatever it is. If I know them personally, than I address them by their first name whatever their username is.
]]>@Qiaochu: as you can see, I tend to use first names for the same reason as Hanche. But on the other hand, I have similar qualms about addressing the likes of Tao. It's quite natural, especially as a student, to feel a bit uncomfortable (it took me till the 3rd year of my PhD to feel comfortable addressing one of my former lecturers by his first name, or even to refer to him by his first name alone).
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