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This section describes comparative structures and related structures. Comparatives represent a complex and difficult problem, and the bracketing policy for comparatives was never finalized. As a result, variation in analysis is more prevalent for comparatives than for simpler constructions.

Basic tools for bracketing the than/that/as-phrase

The than, that, or as is bracketed as either a PP or an SBAR, and a certain amount of variation exists in the choice of PP or SBAR. SBAR is used when the rest of the than/that/as-phrase is a tensed sentence, or when it contains a subject. PP is in general used when the rest of the than/that/as-phrase is a single constituent. There is a tendency to use SBAR when the rest of the than/that/as-phrase is a VP or other predicate tagged -PRD (even if it is a single word) and when the rest of the phrase is dominated by FRAG, though PP may also be used.

The rest of the than/that/as-phrase after the than, that or as is most often bracketed simply with the bracket labels and function tags appropriate for the constituent. It may be dominated by FRAG, particularly if more than one constituent is involved or if the rest of the phrase is a VP or other predicate (but not an S).

The null element *?* is used to indicated missing constituents in the predicate of the than/that/as-phrase. (See  for a more complete description of the uses of *?*.) The null element *?* has the bracket label that the missing constituent would have if present (see section [list:compa:*?*-use]).

Throughout this section on comparatives, alternate bracketings are shown when they seem particularly likely or common (i.e., not all of the possible variants are shown for each example).

A schematic for possible bracketings follows:

  1. PP or SBAR for the than, that or as.

    (PP than/as (xP rest of phrase))


    (SBAR than/that/as (S rest of phrase))

  2. For the rest of the phrase, after the than, that or as:

    • Appropriate bracket label and function tags.

      (PP than (NP ice cream))


      (SBAR as (S (NP-SBJ I) (VP was)))

    • FRAG may dominate.

      (PP as (FRAG (ADJP possible)))


      (SBAR as (FRAG (ADJP-PRD possible)))

    • With predicates, the null element *?* may be used for missing parts of the predicate.

      (SBAR as (S (NP-SBJ I) (VP was (ADJP-PRD *?*))))


The default for most comparative constructions is to Chomsky-adjoin the than/that/as-phrase to the comparative phrase (ADJP, ADVP, NP). If the comparative phrase is an NP modifier, the than/that/as-phrase is adjoined to the entire NP rather than to the modifier.

Examples of several common constructions follow:

  1. AS

    AS — AS

    (ADJP (ADJP as mysterious) (PP as (NP (NP a tiny hole) (PP-LOC in (NP my skin)))))

    AS MUCH — AS —

    (S (NP-SBJ it) (VP might not (VP mean (NP (NP as much) (SBAR as (S (NP-SBJ it) (VP means (PP to (NP us)))))))))

    NOT SO MUCH — AS —

    (NP (NP not (ADVP so much) a search) (PP for (NP truth)) (PP as (PP for (NP certainty))))


    (NP (NP (ADJP as good) a year) (PP as (NP 1989)))

  2. THAN

    —ER THAN

    (ADJP (ADJP friendlier) (PP than (NP (NP a dog) (PP on (NP a picnic)))))


    (ADJP (ADJP more interesting) (SBAR than (S (NP-SBJ I) (VP thought))))


    (ADJP (ADJP more interesting) (SBAR than (S (NP-SBJ I) (VP thought (S *?*)))))

  3. THAT

    SO — THAT

    (ADJP (ADJP so friendly) (SBAR that...)) (ADVP (ADVP so slowly) (SBAR that...))

    SO — A — THAT

    (NP (NP so playful a kitten) (SBAR that...))


    (NP (NP such a playful kitten) (SBAR that...))

Items intervening between the comparative phrase and the than/that/as-phrase

Simple adjunction

The than/that/as-phrase is adjoined as usual to the comparative phrase if the intervening item is another modifier of the same comparative phrase (i.e., not attached at a higher level).

(S (NP-SBJ There) (VP 's (NP-PRD (NP more reading and instruction) (SBAR (WHNP-1 0) (S (NP-SBJ-2 *T*-1) (VP to (VP be (VP heard (NP *-2) (PP-LOC on (NP discs))))))) (PP than (ADVP-TMP ever before)))) .)


If the intervening item is attached at a higher level, the than/that/as-phrase is *ICH*-attached (and the *ICH* null element adjoined) to the comparative phrase.

(S (NP-SBJ it) (VP might not (VP mean (NP (NP as much) (SBAR *ICH*-3)) (PP to (NP German banking)) (SBAR-3 as (S (NP-SBJ it) (VP means (PP to (NP us))))))) . '')

( (S (NP-SBJ (NP More industrial acreage) (PP *ICH*-1)) (VP lies (ADVP-CLR vacant) (PP-LOC in (NP St. Clair county)) (PP-1 than (PP-LOC in (NP (NP any other jurisdiction) (PP-LOC in (NP the St. Louis area)))))) .))

Than/as-phrase containing only one constituent

In most cases, when the than/as-phrase contains only one constituent, the than or as is bracketed as a PP with the single constituent as its complement.

However, when the single constituent is a predicate (i.e., a VP or -PRD), the than or as is often bracketed as an SBAR. The predicate may be immediately dominated by FRAG or S with a null * subject.

  1. with NP

    (S (NP-SBJ I) (VP like (NP cake) (ADVP (ADVP more) (PP than (NP ice cream)))))

  2. with PP

    ( (S (NP-TMP Last year) , (NP-SBJ the average broker) (VP earned (NP (NP $ 71,309 *U*) , (ADJP (ADJP (NP 24 %) lower) (PP than (PP-TMP in (NP 1987)))))) .))


    (ADJP (ADJP (NP 24 %) lower) (PP than (FRAG (PP-TMP in (NP 1987)))))

  3. with VP

    ( (S (NP-SBJ visitors) (VP have (NP (NP more) (SBAR (WHNP-1 0) (S (NP-SBJ *) (VP to (VP do (NP *T*-1))))) (PP than (VP ski)))) .))


    (NP (NP more) (SBAR (WHNP-1 0) (S (NP-SBJ *) (VP to (VP do (NP *T*-1))))) (SBAR than (S (NP-SBJ *) (VP ski))))


    (NP (NP more) (SBAR (WHNP-1 0) (S (NP-SBJ *) (VP to (VP do (NP *T*-1))))) (SBAR than (FRAG (VP ski))))


    (NP (NP more) (SBAR (WHNP-1 0) (S (NP-SBJ *) (VP to (VP do (NP *T*-1))))) (PP than (FRAG (VP ski))))

  4. with -PRD

    ( (S `` (NP-SBJ (NP It) (S *EXP*-2)) (VP 's (ADJP-PRD (ADJP easier) (SBAR *ICH*-1)) (S-2 (NP-SBJ *) (VP to (VP get (ADJP-PRD worse)))) (SBAR-1 than (FRAG (ADJP-PRD better)))) . ''))

  5. with expected

    (S (NP-SBJ (NP The total) (PP of (NP (NP 18 deaths) (PP from (NP (NP malignant mesothelioma) , (NP lung cancer) and (NP asbestosis)))))) (VP was (ADJP-PRD (ADJP far higher) (SBAR than (S (NP-SBJ *) (VP expected))))) .)


    (ADJP-PRD (ADJP far higher) (SBAR than (S (NP-SBJ-1 *) (VP expected (NP *-1)))))


    (SBAR than (FRAG (VP expected)))

    NOTE: if expected occurs in a fleshed-out sentence, a *?* is likely to be used, as in:

    (NP (NP fiscal fourthquarter earnings) (SBAR (WHNP-1 that) (S (NP-SBJ *T*-1) (VP were (ADJP-PRD (ADJP better) (SBAR than (S (NP-SBJ analysts) (VP had (VP expected (S *?*))))))))))

  6. with possible, usual, etc.

    Usually done as a PP with an ADJP complement:

    (NP (NP more) (PP than (ADJP usual)))

    (NP (NP as many (ADJP solidly minority) districts) (PP as (ADJP possible)))

    Rarely done as SBAR:

    (NP (NP as many (ADJP solidly minority) districts) (SBAR as (FRAG (ADJP-PRD possible))))

More complicated than/as-phrases — use of *?*


When the than/as-phrase contains both a subject and a portion of a predicate, these constituents form the basis of an S, and the missing elements (i.e., the elements which are interpreted but not realized) are often represented by *?*. (See  for more details on *?*.)

In the following list, the likelihood of there being a *?* goes from greatest to least.

  1. subject / copular verb / missing predicate (most likely use for *?*)

    In this example, the missing predicate is a PP, assumed to be something like of military value.

    ( (S (NP-SBJ Laos) (VP is (PP-PRD of (NP (NP (ADJP (ADVP no more) purely military) value) (SBAR *ICH*-2))) (PP to (NP (NP Moscow) (NP itself))) (SBAR-2 than (S (NP-SBJ it) (VP is (PP-PRD *?*) (PP to (NP Washington)))))) .))

  2. subject / other main verb / missing direct object

    ( (S (NP-SBJ the Controller) (VP will (VP have (NP (NP the opportunity) (PP for (NP (NP greater usefulness) (PP to (NP good government)) (SBAR than (S (NP-SBJ he) (VP has (NP *?*) (ADVP-TMP now))))))))) .))

  3. subject / auxiliary / missing main verb

    (S (NP-SBJ The submission) (VP would (VP place (NP the issues) (PP-LOC-CLR before (NP the court)) (ADVP (ADVP more readily) (SBAR than (SINV would (NP-SBJ (NP discussion) (PP in (NP the abstract))) (VP *?*)))))) .)

  4. subject / main verb / missing clausal complement

    (S (NP-SBJ the steel strike) (VP lasted (ADVP-TMP (ADVP much longer) (SBAR than (S (NP-SBJ he) (VP anticipated (SBAR 0 (S *?*))))))) .)


    (S (NP-SBJ the steel strike) (VP lasted (ADVP-TMP (ADVP much longer) (SBAR than (S (NP-SBJ he) (VP anticipated (SBAR *?*)))))) .)

  5. subject / auxiliary / auxiliary replaces main verb

    (S (NP-SBJ Bill) (VP ate (NP (NP more hotdogs) (SBAR than (S (NP-SBJ Mary) (VP did (VP *?* (NP-TMP yesterday))))))) .)

    ( (S (NP-SBJ Bill) (VP eats (NP (NP more hotdogs) (SBAR than (S (NP-SBJ Mary) (VP does (VP *?*)))))) .))


    ( (S (NP-SBJ Bill) (VP eats (NP (NP more hotdogs) (SBAR than (S (NP-SBJ Mary) (VP does))))) .))

Superlative + relative clause

Superlatives with relative clauses are bracketed using the standard bracketing for an NP with a relative clause modifying it. There is no comparative structure shown.

(S (NP-SBJ He) (VP was (ADVP altogether) (NP-PRD (NP the (ADJP most combustible looking) man) (SBAR (WHNP-1 0) (S (NP-SBJ I) (ADVP-TMP ever) (VP saw (NP *T*-1)))))))