Install packages with unmet dependencies

alvinsim@ubuntu:/etc/apt$ sudo apt-get install emacs
Reading package lists... Done
Building dependency tree
Reading state information... Done
Some packages could not be installed. This may mean that you have
requested an impossible situation or if you are using the unstable
distribution that some required packages have not yet been created
or been moved out of Incoming.
The following information may help to resolve the situation:

The following packages have unmet dependencies:
emacs : Depends: emacs23 or emacs23-lucid but it is not going to be installed
emacs23-nox but it is not going to be installed E: Broken packages