Multiword expression

Revision as of 17:22, 21 June 2011

Multiword Expressions (MTW) are lexical structures made up of a sequence of two or more lexemes. They can be concatenated ("darkroom", "skinhead") or isolated by hyphens ("blue-green", "African-American") or blank spaces ("round table", "part of speech"). Multiword expressions can be continuous ("get over") or discontinuous ("get <something> together"). They correspond to compounds ("fireman", "hardware"), phrases ("in spite of", "take into account"), idioms ("kick the bucket", "play cat and mouse"), fragments of sentences ("and so on", "whatever the case") or sentences ("Every evil is followed by some good", "No flies enter a mouth that is shut"). Multiword expressions may also include acronyms (such as "UNESCO"), multiple-word contractions (such as "don't") and blends (such as "sitcom") that are still analysable (differently from "radar" and "motel", which are represented as simple words). Classical compounds ("agriculture", "photograph") and their derivations ("agricultural", "photographically") are treated as simple words if they do not include more than one free morpheme. Phrasal verbs ("give in", "come across") are treated as multiword expressions.

Multiword expressions formed with a single inflectional element

Lemma

The lemma of a continuous multiword expression is the multiword expression itself ("part of speech");

The lemma of a discontinuous multiword expression must include the obligatory variables ("behind <person>'s back");

The lemma of a continuous/discontinuous multiword expression is the multiword expression itself ("take into account", "bring back").

Base form

The base form is the same as the lemma, except in case of multiword expressions that involve discontinuity or infixation, i.e., where variations cannot be generated by simple prefixation and/or suffixation rules. In these cases, the base form will correspond to the lemma of the longest common denominator between all the possible variations of the word. The base form must necessarily belong to the same category of the lemma.

For instance:

• coffee house (continuous multiword expression without infixation: "coffee house">"coffee houses"): BF=lemma="coffee house"
• give in (continuous multiword expression with infixation: "give in">"gave in"): BF="give" ≠ lemma="give in"
• behind one's back (discontinuous multiword expression without infixation: "behind my back", "behind his back", etc.): BF="behind" ≠ lemma="behind <person>'s back"
• take into account (discontinuous multiword expression with infixation: "take it into account", "took that into account"): BF="take" ≠ lemma="take into account"

Composition rules

Composition rules are rules that are applied over the base form to generate the lemma. They are used only when the lemma is different from the base form.

For instance:

• coffee house: lemma = base form, composition rule = NULL
• give in: lemma (= give in) ≠ base form (= give), composition rule = VH([in]); (i.e., lemma = base form + "in")
• take into account: lemma ≠ base form, composition rule = VA("into account"); (i.e, lemma = base form + "into account")
• behind one's back: lemma ≠ base form, composition rules = PA([back]); (i.e., lemma = base form + "back")

The composition rules are further described in composition

Inflectional paradigm

The inflectional paradigm and the inflectional rules apply over the base form (and not over the lemma).

For instance:

• coffee house: base form = "coffee house", paradigm = M2 (regular nouns that make the plural in -s);
• give in: base form = "give", paradigm = M1 (irregular), inflectional rules = (PAS:="gave";PTP:="given";);
• take into account: base form = "take", paradigm = M1 (irregular), inflectional rules = (PAS:="took";PTP:="taken";);
• behind <person>'s back: base form = "behind", paradigm = M0 (invariant)

Subcategorization frame

The subcategorization frame refers to the the lemma (and not to the base form).

For instance:

• coffee house: base form = "coffee house", frame = Y0 (avalent);
• give in: base form = "give", frame = Y38 (Somebody ----s something);
• take into account: base form = "take", frame = Y38 (Somebody ----s something);
• behind <person>'s back: base form = "behind", frame = Y1 (irregular), subcategorization rules: PC(NA([back];ANM,GNT));

Multiword expressions formed with several inflectional elements

Multiword expressions may consist of several different inflectional elements. In Latin, for instance, the expression "lingua franca" involves two words: "lingua", a noun, and "franca", an adjective, both inflectional, and the latter must agree with the former in number, gender and case, as follows:

In the UNL^arium framework, the following applies to "lingua franca":

• LEMMA = "lingua franca"
• BASE FORM = "lingua" (because "lingua franca" involves infixation; and "lingua" is the part of the lemma that belongs to the same category of "lingua franca", which is a noun)
• COMPOSITION RULES = NA([francus],M7,FEM,RNUM,RCAS);
  • Where:
  • NA indicates that "lingua" requires a nominal adjunct, which is formed according to the specifications below (enclosed between parentheses):
  • [francus] indicates that this adjunct is made out of the word that has the lemma "francus"
  • M7 indicates that [francus] belongs to the paradigm M7 (adjectives of the type -us,-a,-um)
  • FEM indicates that [francus] must be generated in the feminine form
  • RNUM indicates that [francus] must have the same number of the head of the noun phrase (i.e., "lingua")
  • RCAS indicates that [francus] must have the same case of the head of the noun phrase (i.e., "lingua")
• INFLECTIONAL PARADIGM = M12 ("lingua" follows the first declension of Latin nouns)
• SUBCATEGORIZATION FRAME = Y0 (avalent: "lingua franca" does not require any specifier or complement)

Multiword expressions formed by coordination