Change topic research upon arrival?

[niocwacs]

Supposing that in your essay of background you specified that you're interested in, say, PDEs and inverse problems for dynamic systems, would it be inadequate to tell your preliminary advisor or director of graduate studies upon arrival that you're actually more interested in group theory or number theory?

I mean that you never know what were actual factors that finally made the committee to accept your candidacy. And it might be the case that the main reason that you were accepted was that they wanted for some particular project (especially if the department has a lot to do with various applications in which PDEs are much more promising than algabra) which you now wouldn't participate in as you want to change your field.

So, what's your opinion on the question stated in the first paragraph?

[bgk]

Unless you've been assigned an advisor (which is unlikely for a math program) it should be fine. I'm sure the adcoms realize that people will be a bit unsure about what they want to work on. Don't make a big fuss about it, just take the relevant classes and impress the right professors so they will be interested in taking you.