bachotex2005-frank-mittelbach-pearl1.tex
bachotex2005-frank-mittelbach-pearl1.tex
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%%% Frank Mittelbach: \looseness not so loose (LaTeX) \begin{center} \begin{minipage}{300pt} \font\rm ecrm10 \rm \begin{multicols}{2} This paragraph was set twice in a two column multicols environment. The first time it was set without any special adjustments, the second time we used \texttt{-1} as the value for the \texttt{\textbackslash looseness} parameter. Can you explain why the two paragraphs are differently broken into lines even though clearly the use of the parameter \texttt{\textbackslash looseness} couldn't shorten the paragraph at all? \columnbreak \looseness=-1 This paragraph was set twice in a two column multicols environment. The first time it was set without any special adjustments, the second time we used \texttt{-1} as the value for the \texttt{\textbackslash looseness} parameter. Can you explain why the two paragraphs are differently broken into lines even though clearly the use of the parameter \texttt{\textbackslash looseness} couldn't shorten the paragraph at all? \end{multicols} \end{minipage} \end{center} \paragraph{Answer:} When \verb=\looseness= gets a non-zero value, \TeX{} will always run through all paragraph passes (i.e., breaking without hyphenation, with hyphenation and (if {\tt \string\emer\-gency\-stretch} is non-zero as it is inside multicols) through the emergency-pass. But adding \verb|\emergencystretch| to every line means that the line breaks chosen in the first paragraph may fall in different fitting classes so that at different places \verb|\adjdemerits| are charged, thus making the original solution less attractive. In fact the situation could even be worse: if a long paragraph can be broken into lines by just using \verb|\pretolerance|, then a setting of \verb|\looseness| to \verb|+1| might in fact result in a paragraph with one line less---all that is required is that by breaking it using \verb|\tolerance| we would get a default line count that would be 2 lines less than in the case with \verb|\pretolerance| (a real life example is left to the reader).
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