Not to be confused with group presentation. Representation theory is a branch of mathematics that studies abstract algebraic structures by representing their elements as linear transformations of vector spaces, and studies modules over these abstract algebraic structures.
The signature effect of HIV infection, and the cause of AIDS, is disruption of the T-lymphocyte branch of the immune system and in particular the destruction of CD4+ T-helper cells.
HIV (human immunodeficiency virus) attacks the body's white blood cells -- specifically a subset called CD4 or helper T cells. This attack allows opportunistic infections to take advantage of a weakened immune system, and can lead to illnesses, cancers, or neurological problems.