Porter2

Constants

C

A non-vowel

V

A vowel: a e i o u y

CW

A non-vowel other than w, x, or Y

Double

Doubles created when adding a suffix: these are undoubled when stemmed

Valid_LI

A valid letter that can come before ‘li’ (or ‘ly’)

SHORT_SYLLABLE

A specification for a short syllable.

A short syllable in a word is either:

1. a vowel followed by a non-vowel other than w, x or Y and preceded by a non-vowel, or

2. a vowel at the beginning of the word followed by a non-vowel.

(The original document is silent on whether sequences of two or more non-vowels make a syllable long. But as this specification is only used to find sequences of non-vowel - vowel - non-vowel - end-of-word, this ambiguity does not have an effect.)

STEP_2_MAPS

Suffix transformations used in porter2_step2. (ogi, li endings dealt with in procedure)

STEP_3_MAPS

Suffix transformations used in porter2_step3. (ative ending dealt with in procedure)

STEP_4_MAPS

Suffix transformations used in porter2_step4. (ion ending dealt with in procedure)

SPECIAL_CASES

Special-case stemmings

STEP_1A_SPECIAL_CASES

Special case words to stop processing after step 1a.