I am pretty new to this site. I have a question about setting up a morphological condition. eg.

In a language, we see a pattern that consonant-ending as well as ə-ending words are pluralized with a replacive morpheme {-i}. Can I formulate this condition as this?

ə, ∅ → i / _#

If I can't, what is the correct way of formulating this?

Also please suggest some references from where I can learn the conventions of formulating such conditions which are useful in morphology as well as in historical linguistics.

  • Why the null morpheme?
    – lmc
    Commented Aug 12, 2019 at 12:19
  • 1
    I was committing a mistake there, @jknappen made it clear in the answer.
    – Niranjan
    Commented Aug 12, 2019 at 15:30

2 Answers 2


I think there is a bug in your rule, as you write it, any word can form a plural adding an i, even when the word ends in a vowel.

My corrected version of the rule is

ə → i / _#
∅ → i / C _ #

using a capital C as a metacharacter for any consonant.

BTW, the notation is known as SPE style rules or SPE type rules and goes back to Xerox Finite State Tools (xsft). Some tutorial on the Web are

  • Oh yes! This is definitely making more sense. Thank you. Can you please also suggest some reference material from which I can learn to form the rules correctly?
    – Niranjan
    Commented Aug 12, 2019 at 15:28

"Correct" formulation of rules is relative to some context, for example in the context of a specific theory like Distributed Morphology, or Two Level Morphology. If you are just attempting to describe a fact pattern, a plain English statement would suffice, and in fact is superior to a "formalization", since using a set of symbols the way you did suggests that you are operating in some formal theoretical framework, which doesn't seem to be the case.

The usual way of treating the pattern that you describe is to affix -i in the morphology (no further conditions), and have a separate phonological rule of schwa-deletion (before a vowel, possibly just /i/). That is, "affix -i" regardless of context, then ə→Ø/__V. You don't say what happens with vowel-final words, and that makes a difference. In certain versions of Distributed Morphology, there could not be a rule that simply changes final schwa to i, there has to be a specific triggering context, which would probably lead to positing a general affix /i/ with a peculiar phonological property (in case there are other invariant affixes of the shape /i/ in the language). Work by Shanti Ulfsbjörninn has pushed this particular line of reasoning. In other words, correctness depends on your theoretical assumptions.

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