
 The Mathematics of Face Recognition 
  To begin with, a recognition system has to be invariant both to external changes, like environmental light, and the person's position and distance from the camera, and internal deformations, like facial expression, aging, and makeup. 
  It is clear that we are not working under simple invariant theory, such as Lie group invariants, and that different tools are needed. 
  There are fundamental mathematical results in the literature that try to address these questions and have not yet been fully exploited for face recognition. 
 www.siam.org /siamnews/0403/face.htm (1302 words) 
