FeatureGeometry < Main

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---+ Grammar Engineering Frequently Asked Questions

---++ What is the feature geometry assigned in the Matrix? (Or: How do I figure out what paths I need to use?)

It's not possible to exhaustively describe the feature geometry for at least two reasons:

   1 It's not the same for every sign (consider the features inside COMPS on transitive versus intransitive verbs).
   1 It's not static: Anyone using the Matrix is adding features. Furthermore, depending on how you configured the Matrix (if you're using the modules and the configuration script), you might have slightly different feature sets (e.g., with or without =AUX=).

Nonetheless, it can be useful to have a quick reference guide to the basic feature geometry, especially if you're having a hard time getting path names right. This FAQ attempts to provide that basic guide.

---++ Outermost features

The top level features on all signs are as follows:

   * =STEM= the orthography
   * =SYNSEM= syntactic and semantic constraints
   * =KEY-ARG= is this the daughter that should be instantiated first? (NB: This feature is typically set not in the definition of the sign itself but in the definition of a rule describing which of its daughters should be instantiated first.)
   * =ARGS= daughters (for lexical entries, this is just ignored; for phrase structure rules, it is the daughters, for lexical rules, it is (logically) the input)
   * =INFLECTED= a binary feature which tracks whether a lexical item is completely inflected.

In addition, phrases and lex-rules also have the following:

   * =[[GlossaryC-CONT][C-CONT]]= constructional content (the semantic contribution of the phrase or lex rule)
   * =RULE-NAME= a string giving the rule a name for LKB display purposes

Headed-phrases further have:

   * =HEAD-DTR= the sign that is the head-daughter, linked (by =basic-head-only=, =basic-head-final=, or =head-initial=) to the appropriate element of the =ARGS= list.

Binary headed-phrases have an analogous feature

   * =NON-HEAD-DTR= the sign that is the non-head daughter.

And lexical entries (lex-item) and lexical rules also have the following:

   * =ALTS= a place for features tracking which lexical rules an item can undergo (not well-developed within the Matrix as of 4/2006)
   * =ARG-ST= the argument structure of the lexical item (only on words, but NB we don't do binding theory; =ARG-ST= is used to assist in cross-linguistic statements of linking facts, or the mapping of syntactic and semantic arugments)

---++ Synsem Features

Most of the action happens within =SYNSEM= (either the =SYNSEM= of the sign itself, or the =SYNSEM= of its =ARGS=). Inside =SYNSEM=, one finds:

   * =LOCAL= syntactic and semantic information, excluding that dealing with non-local dependencies.
   * =NON-LOCAL= information about non-local dependencies
   * =OPT= for marking certain arguments as optional or obligatory (note that this feature is usually used by selecting heads inside their valence features)
   * =DEF-OPT= a feature allowing lexical heads to specify how their arguments are to be interpreted (as definite or indefinite) when they are left unxpressed. This may be superseded by a Sem-I based solution. Like =OPT=, signs don't specify their own =DEF-OPT= value, but rather the =DEF-OPT= value of their dependents.
   * =[[GlossaryLIGHT][LIGHT]]= a feature useful for handling phenomena that distinguish words (or word-like small phrases) from phrases (see Abeille and Godard 2003).
   * =MODIFIED= a feature used in the analysis of modification to control spurious ambiguity in the case of left and right modifiers.
   * =LKEYS= pointers into the semantics of lexical items, useful for syntax-semantic linking in defining lexical types.

---++ Local features

Inside =LOCAL=, one finds the following:

   * =CAT= category (head, valence)
   * =CONT= content (semantics)
   * =CTXT= context (pragmatic information; not well developed as of 4/2006)
   * =AGR= (syntactic) agreement
   * =COORD= a feature which distinguishes phrases that are inside of coordinate structures from those that are not.
   * =COORD-REL= a feature which mediates semantic composition in the case of coordination
   * =COORD-STRAT= a feature for distinguishing coordination strategies in languages which have more than one.

---++ Non-local featues

Inside =NON-LOCAL=, one finds the following features, which all take difference lists as their values:

   * =SLASH= long-distance dependencies (topicalization, wh-questions, relativization, easy-adjectives)
   * =QUE= marks the presence of wh- question words within a consituent; used in the analysis of wh-questions
   * =REL= marks the presence of relative pronouns within a constituent; used in the analysis of pied piping in relative clauses

---++ Category features

Inside =CAT=, one finds the following:

   * =HEAD= Part of speech information. NB: as of 4/2006, the Matrix provides a hierarchy of types which serve as the value of =HEAD=, but no features for those types, beyond =MOD= and =KEYS=.
   * =VAL= Valence requirements (specifier, subject, complements)
   * =MC= distinguishes main from subordinate clauses, in case of phenomena sensitive to this distinction
   * =HC-LIGHT= determines the =LIGHT= value of a head-complement phrase with the current item as its head.
   * =POSTHEAD= controls order of modifiers with respect to heads

---++ Head and Valence features

Inside =HEAD=, one finds the following:

   * =MOD= list valued; either a list containing a single synsem that matches the kind of constituent the sign can modify, or empty.
   * =KEYS= fine-grained subclassification of part of speech types (e.g., temporal v. non-temporal nouns, specific adpositions)

Inside =VAL=, one finds the follwing, which all take lists of synsems as their values.

   * =SUBJ= subject of verbs, other predicates
   * =SPR= specifier of nouns, adjectives; as a basic rule of thumb, specifiers are semantic heads, subjects are not
   * =COMPS= complements of any kind of head
   * =SPEC= feature used by specifiers to select their heads (and therefore gain access to information for semantic composition)
   * =--KEYCOMP= pointer to 'key complement' on =COMPS= list.

---++ Content features

Inside =CONT= as well as =C-CONT=, one finds the following:

   * =HOOK= information available for further semantic composition
   * =RELS= list of elementary predications (difference list to facilitate append)
   * =HCONS= list of handle constraints (diffrence list to facilitate append)
   * =MSG= pointer to message on =RELS= list.

The value of =RELS= is a list of elementary predications, which typically have the following features:

   * =LBL= the handle which labels the ep.
   * =WLINK= a list used (by the underlying machinery) for linking an ep to the lexical item that contributed it; useful in some applications
   * =PRED= the predicate name of the relation
   * some list of =ARGn= features, each taking an index or a handle as their value.

The value of =HCONS= is a list of qeqs, which have the following features:

   * =HARG= the handle with higher scope
   * =LARG= the handle with lower scope

Inside =HOOK=, one finds the following:

   * =LTOP= local top handle
   * =INDEX= index (individual or event) of the local sign
   * =XARG= distinguished argument of the local sign, available for control by outside predicates

---++ Lexkeys

Inside =LKEYS= one finds the following:

   * =KEYREL= pointer to main relation in =RELS=
   * =ALTKEYREL= pointer to an alternate relation in =RELS=
   * =--COMPKEY= pointer to the first complement's KEY predsort
   * =--OCOMPKEY= pointer to the oblique complements's KEY predsort

---++ Examples

Here are a couple of pdf files meant to be used as "cheat sheets" for reading of the path names of features you want to constrain in your grammars. They are not complete, but aim to present the most commonly used features in a readable format.

   * [[http://depts.washington.edu/uwcl/docs/geo1.pdf][for phrases]]
   * [[http://depts.washington.edu/uwcl/docs/geo2.pdf][for lexical entries]]
---

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-- Main.EmilyBender - 09 Apr 2006
Topic revision: r8 - 2011-06-01 - jcrowgey