Source : Free On-Line Dictionary of Computing

\sqsubseteq
     
        {LaTeX} name for a symbol like a capital E without the bottom
        half of its vertical line.
     
        In {domain theory},
     
        	x \sqsubseteq y
     
        means x is no more defined that y.  This expression only has
        meaning if x and y are {comparable} elements of some
        {partially ordered set}.
     
        (1994-11-24)