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From text to speech: The MITalk system
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morph types. The first criterion is functional and divides suffixes into derivational
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(“DERIVATIONAL” or “DERIV”) and inflectional (“INFLECTIONAL” or
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“INFL”) types. Derivational suffixes have a major effect on the meaning of a root
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and may change the part of speech (e.g. ness, ment, y). Inflectional suffixes
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merely change the tense, number, or inflection of the root (e.g. ing, ed, s). This
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classification is used primarily by the scoring algorithm.
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The other suffix classification is used solely by the spelling change rules.
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This divides suffixes into vocalic and nonvocalic categories depending on whether
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the suffix begins with a vowel or consonant, respectively. The type names are
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“VOCALIC” (or “VOC”) and “NONVOCALIC” (or “NONV?”).
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The “STRONG” morph type denotes a root which already contains tense or
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number information. This type of morph is a combination of root and inflectional
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morphemes which are not reflected directly in the morph structure. Examples are
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went (20+PAST) and women (woman+PLURAL).
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In addition to free roots, there are two types of bound roots. The “LEFT
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FUNCTIONAL ROOT” (or “LF-ROOT”) is a root which must always be followed
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by a derivational suffix. An example is absorpt in absorptive and absorption. In
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this case (as with many LF-ROOTs), the morph represents a suffix-caused spelling
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mutation of a root morpheme which is too complex or idiosyncratic for the spelling
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change rules to incorporate (e.g. absorb+ive — absorptive). A “RIGHT FUNC-
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TIONAL ROOT” (or “RF-ROOT”) must always be preceded by a prefix. For ex-
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ample, mit in permit, transmit, and submit. These morphs generally have some
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etymological basis (and are not simply repeated letter patterns). For example: the
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root mit is derived from the Latin mittere -- to send; it is just that the root itself
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never became part of the English language and its meaning is overlooked by the
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average speaker.
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The hyphen (-) has its own morph type “HYPHEN”. This is provided so that
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hyphenated words which do not appear directly in the lexicon can be properly
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decomposed.
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3.4.3 Legal morph sequences
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The detection of legal and illegal morph sequences is performed by a finite state
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machine (FSM).
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The grammar recognized by the FSM is summarized in production rules
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below:1
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IThese use Wirth’s notation: = for production, [ ] for optional factors (zero or one rep.), { } for
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repeated factors (zero to infinite repetition), () for grouping, and | for alternatives.
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30
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