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

=== Assistant: 2511131738ET ===
251113_1738ET

short answer: there is a pretty good system, but it’s more “high-probability heuristics” than a fully deterministic decoder. Irish spelling is doing two jobs at once:
* encode vowel phonemes, and
* encode broad/slender consonant quality.

i’ll give you a usable algorithm and then apply it to caife and friends.

==== ### ====
* Broad vowels: a, o, u
* Slender vowels: e, i
* Consonant is: - broad if its nearest vowel(s) are broad, - slender if its nearest vowel(s) are slender.
* The vowel that “does the job” can be before or after the consonant.

This already explains a lot of “mystery vowels”.

===== - Stress is almost always on the first syllable. =====
* Every syllable needs one vowel nucleus (monophthong or diphthong).
* Unstressed vowels are usually /ə/ or disappear.

Heuristic:

: 

===== There’s a finite set of vowel pairs that normally spell one vowel (not two). Examples (simplifying wildly): =====
* ai, ea, eo, ia, io, oi, ui, ua, ae, ao

In many positions, these behave as single vowels. So if you see one of these, first ask:

: 

If a remaining e/i is left over with no obvious vowel job, it’s very often just a slenderizer.

==== Here’s a workable mental algorithm: ====
# Mark stress (almost always first syllable).
# For each syllable, identify candidate vowel digraphs (ai, ea, eo, etc.). - If you can parse V1V2 as a known digraph for that syllable → treat as 1 vowel.
# After that, in each syllable: - Keep one vowel (or digraph) as the “real” sound. - Any remaining isolated e/i that: - sits right next to a consonant, and - would make that consonant slender in line with morphology/other patterns → is probably silent as a vowel, acting only as a class marker.
# Unstressed final -e is almost always /ə/ but also counts as a slenderizer for the preceding consonant.
# If you need a certain consonant to be broad/slender but no sounded vowel of the right class is suitable, one of the extra vowels is doing the “quality only” job.

This won’t catch every dialectal or historical quirk, but it gives you high hit-rate.

==== ### ====

Spelling: c a i f e
Pron: /ˈkafʲə/
# Stress on cai-.
# Vowels in first syllable: a, i. No absolutely obligatory digraph like ae / ao here.
# We want: - broad c (underlyingly; matches lots of forms like cáife etc.) - slender f (because of final e and general pattern of café-type loans)

A consistent parse:
* a = the real vowel /a/ of the stressed syllable.
* i = no independent vowel in the target pronunciation → treat it as mainly a slenderizer for f, but historically also part of a digraphish spelling; in modern standard /ˈkafʲə/ it contributes no separate vowel.
* e (final) = /ə/ and also keeps f slender.

So here the role of i is basically “extra slender support” for f; caife is a loan and a bit messier than native patterns, but this reading is consistent with the system.

===== b a i n n e → /ˈbˠanʲə/ =====
* Syllabify: bainne ≈ bain-ne.
* ai in the first syllable: - Vowel we actually hear: /a/. - a is the syllable vowel; i’s main role is to make n slender.
* Final e = /ə/, and again a slenderizer for preceding n.

So:
* a = real vowel, broad for b.
* i = mostly slender marker (no separate /i/).
* e = real /ə/ + slender marker.

This is a very clean example of “sound vs class marker”.

===== m a i t h → /mˠah/ =====
* First syllable stressed; cluster maith is one syllable.
* ai: vowel heard is /a/.
* a is real vowel; i exists to keep the underlying t slender (even though it surfaces as lenited th [h]).

So ai = [a] + slender flag for the consonant to its right.

===== t a e → /t̪ˠeː/ =====
* Here ae really is a standard digraph → /eː/.
* There’s no extra vowel that “just” marks slenderness; the consonant t is broad anyway.

So ae is firmly type (3): digraph → one monophthong.

===== s i ú c r a → /ˈʃuːkɾˠə/ =====
* ú = long vowel /uː/, easy.
'' i before s: - No extra vowel in the actual sound; we get /ʃuː…/, not ''/siuː…/. - So i’s main function is to make s → ʃ, i.e. slenderize it with no independent vowel.

That’s your prototype of a pure class marker vowel.

==== - For native vocabulary and standard dialects, the above will get you most of the way: - Identify real vowel nuclei per syllable. - Treat leftover e/i as quality markers when they would otherwise create too many vowel sounds. - Respect the broad/slender harmony constraint. ====
* Where it breaks: - Loanwords (caife, traein, stáisiún…) can be a bit orthographically baroque. - Dialect differences (e.g. raibh /rʲɛvʲ/ vs /rʲəvʲ/) shift what you actually hear. - Some morphologically complex forms have historically motivated but opaque vowels.

but if you apply the algorithm:

: 

you’re basically using the same mental model native readers do.

if you want, we can take a random Duolingo batch and I’ll have you try to classify each vowel by role and then we check against IPA.