Editing Openai/69186d20-2d14-8013-b9c6-c09000f173f6 (section)

=== Assistant: 2511131517ET ===
251113_1517ET

Legend (your categories):
1 = only signals broad/slender (not its own vowel)
2 = single-letter monophthong
3 = digraph (etc.) = one monophthong
4 = digraph = diphthong
5 = combo (monophthong/diphthong and broad/slender “bridging”)

===== Dia /ˈdʲiə/ =====
* i + a → ia = /iə/ → 4 + 5 - functions as a diphthong (4) - i also makes d slender (5)

duit /d̪ˠɪtʲ/
* ui = /ɪ/ → 3 + 5 - digraph monophthong (3) - u keeps d broad, i makes t slender (5)

caife /ˈkafʲə/
* a = /a/ → 2
* i = silent, just makes f slender → 1
* e = /ə/ → 2

le /lʲə/
* e = /ə/, makes l slender but is a real vowel → 2 (slender effect is “free”)

do /d̪ˠə/
* o = /ə/, makes d broad → 2

thoil /hɪlʲ/
* oi = /ɪ/ (or /ɔ/ in some dialects) → 3 + 5 - monophthong digraph (3), o keeps t/“th” broad, i makes l slender (5)

===== Bainne /ˈbˠanʲə/ =====
* a = /a/ → 2
* i = silent, just makes n slender → 1
* e = /ə/ → 2

(le / do / thoil as above.)

===== Cáca /ˈkˠaːkə/ =====
* á = /aː/ (long) → 2
* a (final) = /ə/ → 2

go /ɡə/
* o = /ə/ → 2

raibh ≈ /ɾʲɛvʲ/
* ai = /ɛ/ → 3 + 5 - digraph monophthong (3) - a gives broad r, i gives slender bh (5)

maith /mˠah/
* ai = /a/ → 3 + 5 - digraph monophthong (3) - a keeps m broad, i makes (underlying) t slender (5)

agat /ˈaɡət̪ˠ/
* first a = /a/ → 2
* second a = /ə/ → 2

===== Tae /t̪ˠeː/ =====
* ae = /eː/ → 3 + 5 - monophthong digraph (3) - a keeps t broad while the vowel quality is front (5)

agus /ˈaɡəsˠ/
* a = /a/ → 2
* u = /ə/, keeps s broad → 2

siúcra /ˈʃuːkɾˠə/
* i = silent as vowel, just palatalizes s → ʃ → 1
* ú = /uː/ → 2
* a (final) = /ə/ → 2

Big picture:
* Pure “broad/slender only” vowels (1): i in caife, bainne, siúcra (and arguably pieces of duit, maith, raibh if you zoom in).
* Most other vowels are real vowels (2), but of course also determine consonant quality.
* True vowel digraphs in your set: ui, oi, ai, ae, ia; they mostly encode single vowels (3), with ia the clearest diphthong (4), and many of them also act as broad/slender bridges (5).