Implementing the center of a PBW basis of finite dimensional Lie algebras.

Author: tscrim

src/doc/en/reference/algebras/lie_algebras.rst

@@ -7,6 +7,7 @@ Lie Algebras
    sage/algebras/lie_algebras/abelian
    sage/algebras/lie_algebras/affine_lie_algebra
    sage/algebras/lie_algebras/bch
+   sage/algebras/lie_algebras/center_uea
    sage/algebras/lie_algebras/classical_lie_algebra
    sage/algebras/lie_algebras/examples
    sage/algebras/lie_algebras/free_lie_algebra

src/doc/en/reference/references/index.rst

@@ -4778,6 +4778,11 @@ REFERENCES:
 .. [MoPa1994] \P. Morton and P. Patel. The Galois theory of periodic points
               of polynomial maps. Proc. London Math. Soc., 68 (1994), 225-263.
 
+.. [Motsak2006] Olekasandr Motsak. *Computation of the central elements and
+				centralizers of sets of elements in non-commutative polynomial
+				algebras*. PhD Thesis, 2006.
+				https://kluedo.ub.rptu.de/frontdoor/deliver/index/docId/2308/file/Thesis.pdf
+
 .. [MP2019] \M. Montes, D. Penazzi
             "Yarara and Coral v1"
             https://csrc.nist.gov/CSRC/media/Projects/Lightweight-Cryptography/documents/round-1/spec-doc/yarara_and_coral-spec.pdf