Finding all software packages in Debian that provide a particular alternative

The Debian distribution has the [Debian Alternatives System](https://wiki.debian.org/DebianAlternatives) . From the Wiki: > The Debian alternatives system creates a way for several programs that > fulfill the same or similar functions to be listed as alternative > implementations that are installed simultaneously but with one > particular implementation designated as the default. For example many > systems have several text editors installed at the same time. The vi > program is a classic example of an editor that has many > implementations such as nvi, elvis, vim, etc. but which one should be > designated as the default? In general, there are multiple packages in Debian that provide a particular alternative. How does one obtain a complete list of all such packages that exist in the Debian repositories? Let us use the vi alternative as an example. NOTE: Doing such a query against the list of installed packages is easy, but that is not what this question asks.