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java.lang.Object hu.birot.OTKit.dataType.MapForm
public class MapForm
Realizes a probabilistic mapping from Form
to Form
.
In general, a Form from the domain of the mapping is
mapped unto a number of Forms, each with some probability.
Examples: in the case of Gen, the domain is the set of underlying forms and the range of the mapping are the surface forms. In the case of a neighborhood structure, the mapping is from surface forms to surface forms. In the case of a Base, an empty Form maps to possible underlying forms. In the case utter, surface forms are mapped to overt forms. In certain cases the domain and the range of the mapping are disjunct sets, and in other cases they may be the same set.
Such a mapping (in its fullfledged version) can be seen as a (possibly infinite) weighted and directed graph with Forms as its nodes. From each Form in the domain of the MapForm a (possibly infinite) number of edges go to the Forms in the range of the MapForm. These edges leaving some Form are "wellsorted": there is always a first edge, and there is always a next edge subsequent to some previous edge, unless it is the last edge. The edges also have weights written on them.
Consequently, four operations can be done using a MapForm, corresponding to the four basic methods of this class. For any form1 in the domain of MapForm, one can return:
all the forms in the range pointed to by edges leaving form1;
the form in the range which the first edge leaving form1 points to;
the form in the range which the edge subsequent to the one pointing to form_last points to (or a message saying that the last edge has been reached);
the form in the range which a random edge leaving form1 points to.
The weights on the edges play a role in generating a random edge: First, normalize the weights so that they sum up to 1 (that is, divide them by their sum). Then, generate a random number r between 0 and 1. Finally, start enumerating the edges (beginning with the first edge and using the subsequent – successor – operation) and cumulatively sum up the (normalized) weights. Return the edge for which this cumulative sum is first greater than r.
The set of edges leaving a node can also be a transfinite set: in this case the subsequent/successor operation is complemented by the limit operation.
Whenever you construct a new MapForm, you should define all the four operations  in theory. In practice, you usually need only some of them. For instance, specifying the topology (neighborhood relation) requires method MapForm.random for a random walk, and method MapForm.all for a gradient walk. Moreover, if a FormMap maps to an infinite set for a certain form in its range, specifying MapForm.all is even impossible.
This is the reason why the present class is not abstract. All its four methods are specified, even if they are useless (they throw exceptions). You can either override yourself the methods that you are going to use (that is probably the more efficient way to go), or borrow a MapForm from the class MapFormExamples.
A number of static final Forms complement this class, used to return "error messages". When you implement (formally speaking: when you override) the methods, make sure you follow the conventions regarding the use of these "error codes".
MapFormExamples
,
BasicSteps
Field Summary  

static Form 
InfiniteSet
This form is returned by method MapForm.all(Form form1) if form1 maps to an infinite set. 
static Form 
NoMapping
This Form is returned by a MapForm if it does not contain any mapping from the input form. 
static Form 
NoMoreForm
This form is returned by method MapForm.next(Form form1, Form form2) if form2 is the last form to which form1 is mapped. 
static Form 
NotInRange
This form is returned by method MapForm.next(Form form1, Form form2) if form1 does not map to form2. 
static Form 
RndTooHigh
This form is returned by method MapForm.random(Form form1, double rnd) if rnd is too high (in practice, >1), and therefore no Form is returned. 
Constructor Summary  

MapForm()

Method Summary  

java.util.Vector<Form> 
all(Form form1)
Return all the Forms to which MapForm maps from form1 . 
Form 
first(Form form1)
Return the first Form of those to which MapForm maps from form1 . 
Form 
next(Form form1,
Form form_last)
Return the Form subsequent (successor) to form_last from among those to which
MapForm maps from form1 . 
Form 
random(Form form1,
double rnd)
Return a "random" Form from the set of the Forms to which MapForm maps from form1 . 
Methods inherited from class java.lang.Object 

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait 
Field Detail 

public static final Form NoMapping
public static final Form NoMoreForm
next(Form, Form)
public static final Form NotInRange
next(Form, Form)
public static final Form RndTooHigh
random(Form, double)
public static final Form InfiniteSet
all(Form)
Constructor Detail 

public MapForm()
Method Detail 

public Form first(Form form1)
Return the first Form of those to which
MapForm
maps from form1
.
MapForm
maps form1
to a number of Forms, and this
method returns the first one.
If form1
is not in the domain of MapForm
, then
the static Form MapForm.NoMapping
is returned.
If this method is not overridden, it throws an exception. When you override it, make sure you follow the above convention.
form1
 The form in the domain of MapForm
.
MapForm
mapped
to from form1
.NoMapping
public Form next(Form form1, Form form_last)
Return the Form subsequent (successor) to
form_last
from among those to which
MapForm
maps from form1
.
MapForm
maps form1
to a number of Forms, and this
method returns the one that comes after form_last
.
If form1
is not in the domain of MapForm
, then
the static Form MapForm.NoMapping
is returned.
If form1
does not map to form_last
, then
the static Form MapForm.NotInRange
is returned.
If form_last
is the last Form to which form1
map,
then the static Form MapForm.NoMoreForm
is returned.
If this method is not overridden, it throws an exception. When you override it, make sure you follow the above conventions.
form1
 The form in the domain of MapForm
.form_last
 A form in the range of MapForm
.
form_last
in the range of MapForm
, mapped to from form1
.NoMapping
,
NotInRange
,
NoMoreForm
public Form random(Form form1, double rnd)
Return a "random" Form from the set of the Forms
to which MapForm
maps from form1
.
MapForm
maps form1
to a number of Forms, and this
method returns a random one, based on the random number rnd
.
If form1
is not in the domain of MapForm
, then
the static Form MapForm.NoMapping
is returned.
If rnd
is too high (greater than 1), then
the static Form MapForm.RndTooHigh
is returned.
If rnd
is less than 0, then the result is the same as
if rnd
were equal to 0.
If this method is not overridden, it throws an exception. When you override it, make sure you follow the above conventions.
form1
 The form in the domain of MapForm
.rnd
 Random value defining which form to return.
MapForm
mapped to from form1
.NoMapping
,
RndTooHigh
public java.util.Vector<Form> all(Form form1)
Return all the Forms to which MapForm
maps from form1
.
MapForm
maps form1
to a number of Forms, and this
method returns them as a Vector<Form> – supposing that this set is finite.
If form1
is not in the domain of MapForm
, then
a vector containing the static Form MapForm.NoMapping
is returned. If form1
is mapped by MapForm
to an
infinite set, then a vector containing the static Form MapForm.InfiniteSet
is returned.
If this method is not overridden, it throws an exception. When you override it, make sure you follow the above conventions.
form1
 The form in the domain of MapForm.
NoMapping
,
InfiniteSet


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