Erratum
In Paper C, on page 126, Figure 6 (b) and (c) should be:
LRS 1 LRS 2 SMC 1 SMC 2 -8880 -8860 -8840 -8820 -8800 -8780 (b)PMC. LRS 1 LRS 2 SMC 1 SMC 2 -1.362 -1.36 -1.358 -1.356 -1.354 104 (c)20 newsgroups.
The error was the result of a bug in the implementation of LRS and SMC. The correction does not change the discussion and interpretation of the results.
Linköping Studies in Science and Technology. Dissertations, No. 1969