 the Theory of Switching (1959)<br>
Harvard University Press

<P></P><DT><A NAME="nuutila95">50</a>
<DD>E. Nuutila<BR>
<EM>Efficient transitive closure computation in large digraphs</EM><br>
PhD Thesis, Helsinki University of Technology, 1995. <br>
Acta Polytechnica Scandinavica, Mathematics and Computing in
Engineering Series, No. 74.

<P></P><DT><A NAME="goral79">51</a>
<DD>A. Goralcikova and V. Koubek<BR>
<EM>A reduct and closure algorithm for graphs</EM><br>
In Mathematical Foundations of Computer Scien