/usr/share/link-grammar/lt/4.0.regex is in link-grammar-dictionaries-all 5.3.14-1.
This file is owned by root:root, with mode 0o644.
The actual contents of the file can be viewed below.
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 | % This file is mostly empty! Maybe it shouldn't be!
% Other proper nouns.
% We demand that these end with an alphanumeric, i.e. explicitly
% reject punctuation. We don't want this regex to "swallow" any trailing
% commas, colons, or periods/question-marks at the end of sentences.
% In addition, this must not swallow words ending in 's 'll etc.
% (... any affix, for that matter ...) and so no embedded apostrophe
CAPITALIZED-WORDS: /^[[:upper:]][^'’]*[^[:punct:]]$/
% Sequence of punctuation marks. If some mark appears in the affix table
% such as a period, comma, dash or underscore, and there's a sequence of
% these, then treat it as a "fill-in-the-blank" placeholder.
% This matters only for punc. appearing in the affix table, since the
% tokenizer explicitly mangles based on these punctution marks.
%
% Look for at least four in a row.
UNKNOWN-WORD: /^[.,-]{4}[.,-]*$/
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