PDF OF PUBLISHED PAPER HERE

A corrected version of the published paper has been prepared (OCR of PDF to Word, editing, then back to PDF). In addition to correcting  typos this version also changes the punctuation
of the original away from that insisted on by the JNCS publisher. Apart from the punctuation changes all corrections are indicated in red. The scientific content has not been updated  - this
is not a "2nd Edition". Be aware that despite exhaustive checking the copying and editing may have introduced some errors. PDF of the modified manuscript is linked to HERE.