MnSymbol has a
\udotdot command (search for
\udotdot in the comprehensive latex symbol list document), but I don't want to import MnSymbol because of all the side-effects (for instance, it creates
\vec definitions that clash with other
\vec definitions, and its meant to be used with Adobe Minion Pro in particular).
How can I create my own
\udotdot symbol, for use with Computer Modern or Concrete Math?