Simple bracketing

Trees: $\beta$PUsPU, $\beta$PUnxPU, $\beta$PUnPU, $\beta$PUvxPU, $\beta$PUvPU, $\beta$PUarbPU, $\beta$PUaPU, $\beta$PUdPU, $\beta$PUpxPU, $\beta$PUpPU These trees are selected by parentheses and quotes and can adjoin onto any node type, whether a head or a phrasal constituent. This handles things in parentheses or quotes which are syntactically integrated into the surrounding context. Figure 23.7 shows the $\beta$PUsPU anchored by parentheses, and this tree along with $\beta$PUnxPU in a derived tree.

(468)0(468

(469)

Dick Carroll and his accordion (which we now refer to as ``Freida'') held over at Bahia Cabana where ``Sir'' Judson Smith brings in his calypso capers Oct. 13 .[Brown:ca31] 

(469)0(469

(470)

...noted that the term ``teacher-employee'' (as opposed to, e.g., ``maintenance employee'') was a not inapt description. [Brown:ca35] 

  

Figure: $\beta$PUsPU anchored by parentheses, and in a derivation, along with $\beta$PUnxPU

(a)	(b)

There is a convention in English that quotes embedded in quotes alternate between single and double; in American English the outermost are double quotes, while in British English they are single. The contains feature is used to control this alternation. The trees anchored by double quotation marks have the feature punct contains dquote = - on the foot node and the feature punct contains dquote = + on the root. All adjunction trees are transparent to the contains feature, so if any tree below the double quote is itself enclosed in double quotes the derivation will fail. Likewise with the trees anchored by single quotes. The quote trees in effect ``toggle'' the contains Xquote feature. Immediate proximity is handled by the punct balanced feature, which allows quotes inside of parentheses, but not vice-versa. In addition, American English typically places/moves periods (and commas) inside of quotation marks when they would logically occur outside, as in example (471). The comma in the first part of the quote is not part of the quote, but rather part of the parenthetical quoting clause. However, by convention it is shifted inside the quote, as is the final period. British English does not do this. We assume here that the input has already been tokenized into the ``British'' format.

(470)0(470

(471)

``You can't do this to us ,'' Diane screamed . ``We are Americans.'' 

The $\beta$PUsPU can handle quotation marks around multiple sentences, since the sPUs tree allows us to join two sentences with a period, exclamation point or question mark. Currently, however, we cannot handle the style where only an open quote appears at the beginning of a paragraph when the quotation extends over multiple paragraphs. We could allow a lone open quote to select the $\beta$PUs tree, if this is deemed desirable. Also, the $\beta$PUsPU is selected by a pair of commas to handle non-peripheral appositive relative clauses, such as in example ((472)). Restrictive and appositive relative clauses are not syntactically differentiated in the XTAG grammar (cf. Chapter 14).

(471)0(471

(472)

This news , announced by Jerome Toobin , the orchestra's administrative director , brought applause ... [Brown:cc09] 

The trees discussed in this section will only allow balanced punctuation marks to adjoin to constituents. We will not get them around non-constituents, as in ((473)).

(472)0(472

(473)

Mary asked him to leave (and he left)