*** Guide-to-Links ***
W

W is used to attach the subject of main clauses to the wall (hereafter "the wall" means the left-wall). Almost all kinds of main clauses - declaratives, most questions (object-type, subject-type, where/when/why, and prepositional), and imperatives - use a W of some kind to attach to the wall. The only exception is "yes-no" questions, which attach to the wall with Q. See "Q". The WV attaches the main verb of the main caluse to the wall; thus, W and WV form a cycle. See WV for more details.

  +---W------+
  |          |
/////   The dog ran (Wd)
/////       Who did you hit (Wq)
/////       Who is coming (Ws)
/////       To whom did you speak (Wj)
/////       Go away (Wi)
/////       ... like  wedding cakes (We)
/////   The twin (Wa)
/////       That I did not know (Wt)
/////       Why not (Ww)

Note that the wall is automatically inserted at the beginning of every sentence, and is then treated like a normal word; by the connectivity rule, therefore, it must make some kind of connection to the sentence. The wall thus has "W+ or Q+".

W is also used to attach clauses back to coordinating conjunctions in declarative sentences; coordinating conjunctions thus have "CC- & (Wd+ or Wq+ or Ws+)". CC then makes a link back to the subject of the previous main clause.

Wd: Declarative Sentences

Wd is used in ordinary declarative sentences, to connect the main clause back to the wall (or to a previous coordinating conjunction). Nouns carry Wd-, optionally conjoined with their S+ connectors. Wd- on nouns is directly disjoined with C- (used in dependent clauses) and R- (used in some relative clauses); see "C".
      dog: (({@CO-} & Wd-) or ({@CO-} & C-) or R+) & S+

Wq, Ws, Wj: Questions

Wq, Ws, Wj and Ww are used to connect many types of questions to the wall: subject questions (Ws), object questions (Wq), where/when/why questions (Wq and Ww), adjectival questions (Wq), and prepositional questions (Wj). Each of these link types interacts heavily with post-processing. See "SI" for an explanation of Wq and Ws; see "JQ" for an explanation of Wj. The Ww link is used for questioning exclamations in which there is no head verb that can link to the wall. When there is a head verb, then Wq is used.

Wt: Topic sentences

Most sentences start with a subject; a few start with the topic, instead. The Wt link is used to link the topic to the wall. For example:
            +------------B------------+
            |           +-----I*d-----+
    +---Wt--+--Rn-+-Sp*i+---N--+      |
    |       |     |     |      |      |
  /////   that    I    did    not   know
The B link points to the left, from the head-verb (know) to the topic (that). In the above, ther is no way to link the subject (I) to the wall, without crossing the B link. Thus, the Wt link serves to start the sentence.

Wa: Affirmative replies

Wa is used to connect null-verb sentences to the wall. Null-verb sentences typically occur as affirmative answers to questions: "What did you see?" "A red car." "Who was in it?" "John's evil twin." "When did this happen?" "June 10th." Thus:
    +------Wa------+
    |    +----Ds---+
    |    |   +--A--+
    |    |   |     |
  /////  a red.a car.n 

Wi: Imperatives

Wi is used to connect imperatives to the wall.
     +--Wi-+
     |     |
  /////    Go away

Imperative verb forms have "Wi-", conjoined with their complement connectors. Since the imperative verb form is always the same as the infinitive form (and the plural, in every case except "be"), the same expression can be used. Infinitive verbs thus carry

      (Sp- or I- or Wi-) & [complement];

Wc: Coordinating Conjunctions

There are a number of words that serve to link clauses together: coordinating conjunctions like "and" and "but", and subordinating conjunctions like "after" and "because".
      +---CC---+-Wd+
      |        |   |
    John left but he returned later

           +-MVs+-Cs+
           |    |   |
    John left after I saw you

Note that subordinating and coordinating conjunctions use very different linking structures. First of all, both the left-pointing and right-pointing connectors on the conjunctions are different; "but" has "CC- & Wd+", "after" has "MVs- & Cs+". Secondly, coordinating conjunctions connect back to the subject of the previous clause, subordinating conjunctions to the verb. There are several reasons for making these distinctions. First of all, coordinating conjunctions may not be used in relative clauses:

      *The man I tried to hit but Jane stopped me is here
      *The man I tried to stop Jane but she hit is here
      *The man I hit but Jane comforted is here

(There are other constraints on relative clauses: the main noun of a relative clause may not link to something inside an embedded clause. We handle this using Ce and Cs; see "C".) So, we need to prevent these constructions. Coordinating conjunctions have another related property. They may be used to connect clauses in sequence, like subordinating conjunctions. But whereas subordinating conjunctions seem to link in a nested way, with each modifying the last, coordinating conjunctions seem to "leap" over any preceding subordinating conjunctions:

          +------------+-C-+-S-+------+--C--+--S--+
          |            |   |   |      |     |     |
     1. John screamed when I arrived after Sue  left (seems right)

                           +---- ? ---+
          +------------+-C-+-S-+      +--W--+--S--+
          |            |   |   |      |     |     |
     2. John screamed when I arrived but   Sue   left (seems wrong)

          +-------------CC------------+
          +------------+-C-+-S-+      +--C--+--S--+
          |            |   |   |      |     |     |
     3. John screamed when I arrived but   Sue   left (seems right)

We handle this in the following way. In the first place, coordinating conjunctions link to the left not with MVs-, like other conjunctions, but with CC-.

      and but: CC- & W+;
      dog: {R- or C- or (W- & {CC+})} & S+...;

Note that subject nouns may make a CC connection to the right, but only if a W is being made to the left (i.e., if the noun in a subject of a main clause), not if a C is being made. In other words, while subordinating conjunctions connect to the main verb of the nearest clause to the left, coordinating conjunctions connect to the subject of the nearest main clause to the left. Thus ex. 3 above is allowed, but ex. 2 is prevented. The problem with relative clauses is solved also. In relative clauses, the main subject of the relative always makes either a C- or an R- to the left, and neither one is conjoined with CC+; so no coordinating conjunctions can appear.

Note that the above expressions also allow coordinating conjunctions to link clauses in sequence:

          +-------CC---+--W-+---CC--+-W-+
          |            |    |       |   |
        Jane screamed and Fred ran but Dave cried

Coordinating conjunctions may also connect directly to the wall: "And Jane screamed". Thus they carry a "Wc-" connector, which can link to the wall's W+. Furthermore, a coordinating conjunction may link to a following question, rather than to a declarative clause. They may not, however, link from a question to a declarative clause:

   I know you don't like Joe, but why did you send him that nasty note
   *Why did you send Joe that nasty note, but I know you don't like him

Thus we give such conjunctions the following:

    (CC- or Wc-) & (Wd+ or Wq+ or Ws+ or Qd+);

Another reason for distinguishing between W and C is that certain openers like participle openers may be used in main clauses but not dependent ones; see "CO: Participles as openers".

Fat links are deprecated and disabled by default.
Some of the uses of coordinating conjunctions using CC are duplicated by "fat-link" parses: the special hard-wired system for handling conjunctions (see the "Introduction" document for explanation). A sentence like "Jane screamed and Fred ran" will therefore receive two parses, one using "fat-links" and the other using regular links.
Fat links are deprecated and disabled by default.

We: Ellipses

We is used to connect ellipses to the wall.
     +---We--+
     |       |
  /////     ... like a shot
An ellipsis denotes the intentional ommission of a part of a sentence. Very little can be assumed about what has been omitted, other than that it must have been grammatical. Thus, We- is conjoined with a reasonably broad set of generic links, so that the trailing phrase can parse properly.

Grammar Documentation Page.