2nd declension genitive formation

Motivation

Due to the Standard's inconsistent wording, it is not useful as a reference. As such, this page will document the research I did on the 2nd declension nouns' genitive formations. The goal is eventually to have a set of parameters that, given that a noun is in the 2nd declension, can be used to reliably transform nominative forms into genitive forms.

Examining the data that is in the database, these are the patterns I have noticed.

Transformation types

These patterns exhaustively match all valid 2nd declension nouns in the database.

Pattern Name	Mutation of nominative
+ e	Add -e to Nominative
Palatalization + e	Palatalize according to normal rules and add -e
Alternative Palatalization + e	Like previous, palatalized normally except ea becomes ei, then add -e
í	íoch -> í
aí	ach -> aí
íne	íon -> íne
ingthe	ingt -> ingthe
Syncope + e	Syncopate nominative and add -e
Palatalized syncope + e	Syncopated, then palatalized normally, then add -e
Alternative Palatalization Syncope + e	Like previous, palatalized normally except ea becomes ei, then add -e
Exception	Don't follow above rules, but still are 2nd declension. scian, caileann, blocshliabh

General Patterns

• As noted by the Standard, all of them are feminine, end with consonant in nominative, and end with -e, aí, or í in the genitive. From this point on the change will be noted with respect to the nominative.
• Nouns ending on slender consonants do not ever undergo any palatalization directly. If there is palatalization done, it is first syncopated.
• There are some exceptional transformations that don't appear to apply to any other nouns:
  • scian -> scine -- The a is simply dropped
  • caileann -> caille -- The ann is simply dropped
  • blocshliabh -> blocsléibhe -- While the -liabh is changed to -léibhe, note that the shl is also unlenited.
• There was only one -ingt word in the database, tuirlingt, but the same transformation applies to tarraingt, so I think that is enough to note as its own rule.
• The vast majority of nouns that end on slender consonants will get +e.
• If it ends on a slender vowel, it is always i. (Just an Irish thing, perhaps?)

Working rules

There may be more general patterns that I am missing.

Special endings

• Nouns in the í, aí, íne, and ingthe groups and exceptions will follow those always. Otherwise, generally, the following rules apply.

Slender consonant endings

• For nouns ending in slender consonants, the Alternative Palatalization Syncope + e rule applies to:
  • obair and all compounds thereof
  • domhain
  • seamair
  • sluasaid
  • fothair
• Syncope + e applies to:
  • i + [gd]h + i + consonant
  • -short vowel/í + [tfd] + ir
  • some words ending in consonant + il, but there's no reliable way to tell which ones. E.g. scidil -> scidile, but caibidil -> caibidle
  • -inis
  • trilis
• Almost all other nouns ending in slender consonants, however, simply just get +e.

Broad consonants endings

• What the standard was trying to say is that only beann and circe are the exceptions where ea is changed to i in monosyllabic nouns. Every other monosyllabic noun ending on ea + consonant is changed to ei.
• For polysyllabic nouns, the ea may be any of Syncope + e, Palatalized + e, or Palatalized Alternative + e. There does not seem to be any correlation between syllable stress and rule. There are some patterns that apply, that probably need more elaboration later.
• All nouns ending in broad consonant clusters that are not -ea are just Palatalized + e.