Papers in PDF format

The applet is organised around two main displays which are constructed with components from the Java Abstract
Window Toolkit: the input display accepts user input (sentences, category assignments and phrase structure rules) while
the output display prints tree representations of successful analyses generated by the user's grammar (the input display is
shown in the first two images; the output display in the third).
Sentences chosen by users are separated into tokens (words) next time they click on a button. The category input fields
are adjusted accordingly, showing one labeled field for each word token. When the user clicks on the Parse button, the
input format is verified before it is passed to a parser object as a object made up from objects
consisting of a syntactic category and the graphemic representation, and a object made up by objects.
The parser object then runs its parsing method. A left-corner algorithm implemented as a while-loop rather than relying
directly on recursion is used. This type of algorithm makes it easy to handle left-recursive rules and keep track of choice
points (if one is found a copy of the current state are saved for each alternative which is then pursued in turn). As the
parser proceeds, it constructs a bracketed string representation of the grammatical structure, and successful parses are
saved to an array.
If one or more analyses are found, the applet shifts to the output display. Tree representations of the sentence structure
are painted by sending messages containing a single string representation, the total number of successful analyses and
the number of the current one to the display. The string is then parsed by a second top-down predictive parser, which
generates a set of relative coordinates for the nodes of the tree which are linked and labeled.
The applet can be accessed at URL http://www.linguistics.bangor.ac.uk/java/lt/LingTutor.html.