  Let I be an ideal of a regular local ring Q with residue field k. The length
of the minimal free resolution of R=Q/I is called the codepth of R. If it is at
most 3, then the resolution carries a structure of a differential graded
algebra, and the induced algebra structure on $Tor_Q(R,k) provides for a
classification of such local rings.
  We describe the Macaulay2 package CodepthThree that implements an algorithm
for classifying a local ring as above by computation of a few cohomological
invariants.
