Projection
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This is done by a set of rules as follows: | This is done by a set of rules as follows: | ||
| − | ; | + | ;first intermediate projection (lower XB) |
XC(%head;%comp)<nowiki>:=</nowiki>XB(%head;%comp); | XC(%head;%comp)<nowiki>:=</nowiki>XB(%head;%comp); | ||
:projects the first intermediate projection (XB) in case of comp | :projects the first intermediate projection (XB) in case of comp | ||
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:projects the first intermediate projection (XB) when there is no comp or adjt (the second argument is empty) | :projects the first intermediate projection (XB) when there is no comp or adjt (the second argument is empty) | ||
;second intermediate projection (if any) | ;second intermediate projection (if any) | ||
| − | XB(%head;%xb1)XA(%head;%adjt)<nowiki>:=</nowiki>XB(XB(%head;%xb1);%adjt | + | XB(%head;%xb1)XA(%head;%adjt)<nowiki>:=</nowiki>XB(XB(%head;%xb1);%adjt); |
:projects the second intermediate projection (XB) in case of adjt (the tree has a comp and a adjt, or two adjts) | :projects the second intermediate projection (XB) in case of adjt (the tree has a comp and a adjt, or two adjts) | ||
| − | XB(%head;%comp1)XC(%head;%comp2)<nowiki>:=</nowiki>XB(XB(%head;%comp1);%comp2 | + | XB(%head;%comp1)XC(%head;%comp2)<nowiki>:=</nowiki>XB(XB(%head;%comp1);%comp2); |
:projects the second intermediate projection (XB) in case of comp (the tree has two comps) | :projects the second intermediate projection (XB) in case of comp (the tree has two comps) | ||
;third intermediate projection (if any) | ;third intermediate projection (if any) | ||
Latest revision as of 13:37, 28 August 2012
Projection is the mechanism by which, in a given syntactic tree, one or two constituents are integrated into a more complex structure. It is the bottom-up movement of merging or collapsing one or two subordinate nodes into a higher node in order to form a syntactic structure. In the UNLarium framework, projection is used to build the sentence structure out of the individual constituents (head, specifier, adjunct and complement) during natural language generation.
Contents |
Use
Projections are used to build trees out of the head-driven relations, i.e., to go from:
XS(head;specifier);, which describes the relation between the head of the structure and its specifier XA(head;adjunct);, which describes the relation between the head of the structure and its adjuncts XC(head;complement);, which describes the relation between the head of the structure and its complements XH(head);, which describes the head of the structure
to:
XP
/ \
spec XB
/ \
XB adjt
/ \
X comp
|
head
This is done by a set of rules as follows:
- first intermediate projection (lower XB)
XC(%head;%comp):=XB(%head;%comp);
- projects the first intermediate projection (XB) in case of comp
XA(%head;%comp):=XB(%head;%adjt);
- projects the first intermediate projection (XB) in case of adjt (i.e., when there is no comp)
XH(%head):=XB(%head;);
- projects the first intermediate projection (XB) when there is no comp or adjt (the second argument is empty)
- second intermediate projection (if any)
XB(%head;%xb1)XA(%head;%adjt):=XB(XB(%head;%xb1);%adjt);
- projects the second intermediate projection (XB) in case of adjt (the tree has a comp and a adjt, or two adjts)
XB(%head;%comp1)XC(%head;%comp2):=XB(XB(%head;%comp1);%comp2);
- projects the second intermediate projection (XB) in case of comp (the tree has two comps)
- third intermediate projection (if any)
XB(XB(%head;%xb1);%xb2))XA(%head;%adjt):=XB(XB(XB(%head;%xb1);xb2);%adjt)); (the tree has one comp and two adjts, two comps and one adjt or three adjts)
- fourth intermediate projection (if any)
...
- maximal projection
XB(%head;):=XP(XB(%head;););
- minimal tree: the tree has only the head (no comp, adjt or spec)
XB(%head;%xb):=XP(XB(%head;%xb););
- the tree has only one intermediate projection and no spec
XB(%head;%xb)XS(%head;%spec):=XP(XB(%head;%xb);%spec);
- the tree has only one intermediate projection and the spec
XB(%head;%xb):=XP(XB(%head;%xb););
- the tree has only one intermediate projection and no spec
XB(XB(%head;%xb1);%xb2)XS(%head;%spec):=XP(XB(XB(%head;%xb1);%xb2);%spec);
- the tree has two intermediate projections and the spec
XB(XB(%head;%xb1);%xb2):=XP(XB(XB(%head;%xb1);%xb2););
- the tree has two intermediate projections and no spec
etc.
Syntax
Projection rules are S-rules of the replace type, i.e.:
<RELATION> := <RELATION>;
Where <RELATION> is a syntactic relation, including a <HEAD>, in case of head-only relations (VH, NH, PH, JH, AH, CH, IH, DH), or a <HEAD> and a <ARGUMENT>, in case of binary relations (VC, VS, VA, NC, NS, NA, etc.).
There are mainly two types of projection rules:
- Replace, when the number of relations in the left side is the same as in the right side, and which is used for collapsing single-branched structures (i.e., parent nodes that have one single child)
- Merge, when the number of relations in the left side is greater than in the right side, and which is used for collapsing double-branched structures (i.e., parent nodes that have two children).
Examples
- VH(%head):=VB(%head);
- The head of the verbal phrase becomes the head of the verbal intermediate projection (VB)
- VC(%head;%comp):=VB(%head;%comp);
- The head of the verbal phrase becomes the head of the verbal intermediate projection and the complement of the verbal phrase becomes the second argument of the verbal intermediate projection
- VB(%head;%comp)VA(%head;%adjt):=VB(VB(%head;%comp);%adjt);
- The verbal intermediate projection becomes the head of a higher intermediate projection that takes the adjunct to the verb as second argument
