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Swedish writing conventions states that in compound words, when three successive identical consonants occur, one of them should be omitted. An example of this is glass (ice cream) and strut (cone), which form the compound word glasstrut (ice cream cone), not glassstrut.

Another example is ägg and gula, which forms äggula (egg yolk), not ägggula.

It might seem like a strange rule, and sometimes it creates strange results. As an example, it is impossible to distinguish between the written words glass-strut (ice cream cone) glass-trut (a gull made of ice cream) and glas-strut (a cone made of glass), but most words don't have this ambiguity (äggula can't mean anything else besides egg yolk regardless how it's pronounced).

However, if a hyphenation occur between the two consonants, the third one should be added. This means that äggula should be hyphenated as ägg-gula. Other examples would be till-låta, till-lämpa, topp-position.

Is it possible to achive this kind of hyphenation with Latex? Ideally, I am searching for a solution both for the whole document (like \hyphenation works, for i.e. äggula) and in the text, for cases like glasstrut which could be hyphenated differently depending on the meaning (glass-strut, glass-trut).

Testing shows that none of the above words gets correct hyphenation (using Polyglossia and Xelatex). If I add an entry manually with \hyphenation, I get the hyphenation at the correct place, but I don't know how I could add the "missing" letter.

Oh Norrmalmsregleringen, ho samt Västerbron och Tranebergsbron. glasstrut krigsåren var Larsson även en ledande nordisk 

(Hyphenation should occur in the word "glasstrut", the other words are just there for filling)

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Welcome to TeX.sx! nice examples. there's a command \discretionary that can be used to do what you want, but i don't use it often enough to write an answer off the top of my head; i'll have to look it up. (unless someone else gets there first.) –  barbara beeton Dec 16 '12 at 14:58

2 Answers 2

up vote 9 down vote accepted

No, it's not possible with XeTeX, but something can be done with LuaTeX.

When (Xe)TeX decides for a possible hyphenation point it basically adds \discretionary{-}{}{}, while in the case of "äggula" you want


and this is usually solved by something like

\newcommand{\ggg}{gg\discretionary{-}{\allowhyphens g}{}}

and inputting the word as

ä\ggg ula

(\allowhyphens allows TeX to break also the remainder of the composite word).

Cases like "glasstrut" where semantics is involved are best solved by not allowing hyphenation, resorting to manual insertion of \discretionary (maybe hidden in a macro) in cases splitting the word becomes necessary. See exercise 14.8 in the TeXbook (page 96).

With LuaTeX the situation is very different; you can specify


(there's no point in adding a new hyphenation point "äggu-la", I believe). Minimal example:




The three pairs of braces specify what's in the "pre-break", "post-break" and "no-break" parts just like the arguments to \discretionary.

enter image description here

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where there's more than one of the possible different-but-lookalike words in a document, one could use different macros to identify them, with the \discretionary value built in. (this happens in english too, though almost never with different spelling. for example, \newcommand{\recordnoun}{rec\discretionary{-}{}{}ord vs. \newcommand{\recordverb}{re\discretionary{-}{}{}cord.) @egreg -- do you really want \allowbreaks there? that would presumably allow a break after a third g. the answer to exercise `4.8 (p.314) doesn't have one. –  barbara beeton Dec 16 '12 at 15:27
@barbarabeeton Thanks, I was thinking to \allowhyphens. –  egreg Dec 16 '12 at 15:58
Good answer, solves my problem. The Luatex solution was exactly what I was looking for, looks like I might switch to Luatex in the near future. –  Ahlqvist Dec 16 '12 at 17:25

There is in fact a functionality for these situations built into the babel-package (however not in polyglossia what I have seen). Specifically, the command is


for ff to be hyphenated as ff-f. Used for compound words, such as stra"ffånge, which should be hyphenated as straff-fånge. This is also implemented for b, d, f, g, l, m, n, p, r, s, and t.

Here I have cited the documentation page found as /usr/share/doc/texlive-doc/generic/babel-swedish/swedish.pdf in my distro (TeXlive/Debian).

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