Combinatorica is "obsoleted" since version 8 of Mathematica and there are several symbol names that conflict with built-ins. However, Combinaotrica still contains many useful functions that are not available elsewhere. Because of the name conflicts, after loading Combinatorica you need to explicitly specify whether you're referring to a built-in symbol or a Combinatorica symbol, e.g. System`Graph or Combinatorica`Graph
Many find ti convenient to load Combinatorica as
Block[{$ContextPath}, Needs["Combinatorica`"]]
This won't add the package to the context path, so there won't be name conflicts. But now you need to explicitly use the context of
every Combinatorica symbol (i.e. write Combinatorica`Automorphisms instead og Automorphisms), not just conficting ones such as Graph.
