  In this paper, we study the nature of entanglement in quantum Grover's and
Shor's algorithms. So far, the authors who have been interested in this problem
have approached the question quantitatively by introducing entanglement
measures (numerical ones most of the time). One can ask a different question:
what about a qualitative measure of entanglement ? In other words, we try to
find what are the different entanglement SLOCC classes that can be generated by
these two algorithms. We treat in this article the case of pure four-qubit
systems.
