Prolog commands

 The (intermediate) results of a parse can be inspected by the command show_item(ItemNumber) . This predicate displays the information which is contained in the chart item with ItemNumber. For example, if the LexGram parser told you that one of the results of the parse has been stored in item number 2, you can see its contents by typing

       

|?- show_item(2).
  +-- parse_result
  |'ITEM-ID': !(2)
  |'FROM-TO': !(0-1:[der])
  |'TRACES': !([])
  |'CAT-NAME': !(dp/n)
  |'CAT': +-- word
  |       |root: +-- root
  |       |      |syn: dp
  |       |      +--
  |       |leaves: [
  |       |        \ +-- goal
  |       |        \ |root: +-- root
  |       |        \ |      |syn: n
  |       |        \ |      +--
  |       |        \ |leaves: []
  |       |        \ |slash: []
  |       |        \ +--
  |       |        ]
  |       +--
  |'DTRS': !([leaf(der)])
  +--

parse_result is a built-in type with the following features. (For efficiency reasons, most of the feature values are instances of the prolog type, which is indicated by the !-operator.)

• 'ITEM-ID' is the item number
• The 'FROM-TO' value shows that the substring [der] is covered by the item between the string positions 0 and 1.
• 'TRACES' indicates the multiset of traces which have been used as resources in addition to that substring, i.e. here this set is empty.
• The value of the 'CAT-NAME' feature is a categorial style shorthand of the cat-feature structure, i.e. it abbreviates the structure written under the feature 'CAT'.
• The 'CAT' value is the cat-feature structure for the item.
• The value of the 'DTRS' feature is the list of the daughters of that node

WARNINGS:

• Elementary traces cannot be displayed by show_item. Inspect the licensing category instead.
• The structure sharing among the feature structure proper and the residuated goals for the item will not be shown.

The Prolog query

| ?- bagof(N,show_item(N),_).

will enumerate all the chart items which have been produced during the derivation.

By the call of the predicate show_tree(ItemNumber)  a shorthand form of the derivation tree which is rooted in the item with ItemNumber is displayed. For example, the tree whose root is item 10 is shown by the command

| ?- show_tree(10).
vp:10
   dp:9
      dp/n:2
         der
      n:8
         mann
   vp\dp:5
      geht

The tree-internal numbers are also item numbers. The leaf nodes are either labeled with the individual words or with the symbol  t for 'trace'. The preterminal node of a trace is labeled with the same information as the category which licenses that trace. The goal category for a given sentence has the `item number'  0.