In the above-cited paper, which appeared in the IEEE Transactions on Knowledge and Data Engineering, vol. 19, no. 8, pp. 1116-1130, Aug. 2007, some information appeared incorrectly. We apologize for the error. Please see the list of corrections:
- On p. 1118 in [ 1], in the paragraph above Definition 1, "follows:." should have been "follows:"
- On p. 1122, right column, line -16 from the bottom, " $b E\!\!:\!\!B\;a$ " should have been " $b\; E\!\!:\!\!B\;a$ ."
- 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).