• On p. 1118 in [ 1], in the paragraph above Definition 1, "follows:." should have been "follows:"
• On p. 1123, the display equation in Proposition 2 appeared incorrectly.
Instead of appearing as:
It should have appeared as:
• On p. 1126, right column, line -7 from the bottom, the following equation:
should have appeared as:
• On p. 1129, the Acknowledgments section was left out. It should have appeared as shown below:
Acknowledgments. This work has been partially supported by PENED 03, a project cofunded by the European Social Fund (75 percent) and the General Secretariat of Research and Technology (25 percent).
• S. Skiadopoulos is with the Department of Computer Science and Technology, University of Peloponnese, Karaiskaki Street, 22100, Tripoli, Hellas. E-mail: email@example.com.
• N. Sarkas is with the Department of Computer Science, University of Toronto, 10 King's College Road, M5S 3G4, Toronto, ON, Canada.
• T. Sellis is with the School of Electrical and Computer Engineering, Computer Science Division, National Technical University of Athens, 9, Iroon Polytechneiou Street, GR-15773 Zographou, Athens, Hellas.
• M. Koubarakis is with the Department of Informatics and Telecommunications, National and Kapodistrian University of Athens, Panepistimiopolis, Ilisia, Athens 15784, Greece. E-mail: firstname.lastname@example.org.
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