RE: logos, symbols, and ligatures

From: Philippe Verdy (
Date: Mon Nov 05 2007 - 09:41:27 CST

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    Jeroen Ruigrok van der Werven wrote:
    > German is like Dutch, for all I know, in the ways you hyphenate words
    > (typically on a syllable basis). And the way you hyphenate determines
    > whether or not you can use ligatures or not. So I have to agree with
    > Werner here, the syllable boundary stops the ligature formation.

    Not really. The syllable boundary stops ONLY SOME ligature formations. It
    does not prevent for example the "ff" ligature, because the two letters are
    (almost) always occurring over a syllable break (except at end of a word).
    The "ff" ligature is an example where ligation occurs for aesthetical

    In fact, the rule that determines if syllable break are disallowed is based
    on radicals, not on syllables: in a compound word, it doesnot matter if a
    radical is multisyllabic, as ligatures are permitted everywhere in the
    radical, but not across a radial boundary. The rule however is constrained
    by the type of ligature:

    * the ess-tsett, for example, is a ligature that obeys additional
    constraints, where syllable breaks are still significant, and not just the
    radical break; for this reason, no ess-tsett is allowed in the verb
    "müssen", despite there's only one radical (but two syllables), but it is
    preferred in the "muss" conjugated form (but not in Swiss German where the
    ligature is now deprecating).

    * in "Straffen", the "ff" ligature is permitted, because there's only one
    radical, even if there are two syllables. The syllable break does not
    prevent the ligature, because there's no compound word in German where a
    single final "f" of a radical is followed by another "f" from the initial of
    the next radical (the reason is that there's normally no single "f" at end
    of a radical, it is always a double "f" in this case, and the ligature is
    permitted there).

    A double f ligature may occur in final position of a radical, but the
    radical may still have derived forms with plural or genitive suffixes or
    conjugated suffixes without loosing the ligature. BUT the ligature is still
    hyphenatable (if the hyphenation respects other typographical rules such as
    not isolating a few letters on a line, this minimum number of letters
    varying according to style, but being typically at least 3).

    In French the situation is similar, ligaturing the "ae" letters is almost
    always permitted, but there are similar exceptions, and it is the radical
    break that prevents the ligature, not the syllable break (The city of
    "Caen", one syllable in modern French, is an exception for etymological
    reasons: the "ae" ligature would have the phonetic value of "e" and this
    would change the pronunciation of the leading "C" if the "a" was not kept).

    The same thing is applicable to the ligature of "oe": the ligature is
    permitted (and normally mandatory) each time the "o" is silent or does not
    break the radical, but it is forbidden if there's a radical break (the
    silent "o" was kept for etymological reasons, sometimes not justified, but
    it is justified in a word like "cœur" to prevent pronouncing it like in
    "minceur" with the vocal mutation of "c" into "s").

    In other words, the set of rules for allowing or forbidding a ligature is
    not only specific to each language, but also within each language, specific
    to each ligature. That's why I don't think a any general purpose renderer
    can appropriately infer the presence or absence of ligatures: this requires
    the help of language identification, knowledge of the language-specific
    radicals and allowed mutations and suffixes used for derived forms.

    This job is part of a spellchecker, that must help the renderer by inserting
    ligature hints (ZWJ) or using a dedicated character (the "ae letter" in
    Unicode is a ligature in some languages) everywhere ligatures are permitted
    (and preferable or sometimes mandatory). A renderer alone should NOT take
    the decision of creating a ligature (and it should not be required to use
    ZWNJ in texts to prevent a renderer of doing this: ZWNJ will be used to
    prevent only a spell-checker to suggest a ligature, and ZWNJ should be
    completely ignored by renderers).

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