SIMBAD references

Four questions are asked related to galaxies and their environments in the context of sepculation as to which direction the field may go over the next decade. These are: What is a galaxy? Where does a galaxy end? Are galaxies open or closed? and How important are interactions? In the process, these questions touch upon some of the challenging problmes facing us today in extragalactic astronomy, such as galaxy formation and evolution, the importance of environemntal effects, and the nature and extent of dark matter.