Kang, Andy N. C.Shen, Stewart N.T.2013-06-192013-06-191974http://hdl.handle.net/10919/20253In this paper, the definability of functions over B_s is first briefly discussed. We then give necessary and sufficient conditions on the definable functions over B_2, boolean algebra of four values. An efficient algorithm is also presented for finding the defining boolean expressions for the definable functions over B_2, The result is then extended to the functions over B_s.application/pdfenIn CopyrightTechnical reportCS74007-Rhttp://eprints.cs.vt.edu/archive/00000761/01/CS74007-R.pdf