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[Groff] [Heirloom] Paragraph adjust "badness" calculation

From: carsten . kunze
Subject: [Groff] [Heirloom] Paragraph adjust "badness" calculation
Date: Sat, 1 Aug 2015 14:36:15 +0200 (CEST)


address@hidden ( did notice a major issue in one of 
the key features of Heirloom roff which is paragraph-at-once formatting.  
Gunnar very likely did implement this algorithm based on the 1981 Knuth-Plass 
paper (KP-81 in the following text) and had maybe not been aware that TeX had 
implemended a slightly different algorithm later after gaining more experience 
in that field (TeX82 in the following text).  But even KP-81 is implemented 
incorrectly to such a degree, that paragraph formatting in current Heirloom is 
noticeable far from being optimal.  The full story of reffort's analysis and 
change proposal can be read at

There are two issues in Heirloom with that.  One is the scaling of the 
deviation from the ideal interword space size (which allows too tight lines).  
A second issue is the use of that scaled value in the badness and demerits 
calculation.  Here Gunnar maybe did misinterpret KP-81, the implementation is 
obviously wrong.

reffort did not only provide a solution for these issues, he also provided a 
test document and the possibility to process this document with the algorithm 
described in KP-81, TeX82, two new proposals and current Heirloom (see

Heirloom users are encouraged to test these algorithms (also with their own 
documents) so a final decision regarding the changes could be made.


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