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Java API for Natural Language Generation

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/*
 * The contents of this file are subject to the Mozilla Public License
 * Version 2.0 (the "License"); you may not use this file except in
 * compliance with the License. You may obtain a copy of the License at
 * https://www.mozilla.org/en-US/MPL/
 *
 * Software distributed under the License is distributed on an "AS IS"
 * basis, WITHOUT WARRANTY OF ANY KIND, either express or implied. See the
 * License for the specific language governing rights and limitations
 * under the License.
 *
 * The Original Code is "Simplenlg".
 *
 * The Initial Developer of the Original Code is Ehud Reiter, Albert Gatt and Dave Westwater.
 * Portions created by Ehud Reiter, Albert Gatt and Dave Westwater are Copyright (C) 2010-11 The University of Aberdeen. All Rights Reserved.
 *
 * Contributor(s): Ehud Reiter, Albert Gatt, Dave Westwater, Roman Kutlak, Margaret Mitchell, and Saad Mahamood.
 */

package simplenlg.features;

import simplenlg.framework.ElementCategory;
import simplenlg.framework.LexicalCategory;
import simplenlg.framework.PhraseCategory;

/**
 * 
 * This class defines a list of constant values used by SimpleNLG lexicons. Note
 * that there are three feature classes in SimpleNLG.
 * 

 *  Feature: features typically set up developers invoking
 * SimpleNLG
 * 
 LexicalFeature: features typically set up the SimpleNLG
 * lexicon
 * 
 InternalFeature: features typically used internally by
 * SimpleNLG
 * 
 * 
 * Elements in the system can, in theory, take any kind of feature. Some
 * features will only be expected by certain processors, however. Developers can
 * define their own features but should choose names that do not conflict with
 * those presented here.
 * 
 * 
 * The details for each feature are supplied in a table. The entries are:
 * 
 * 
 * 
 * 
 * 
 * 
 * 
 * 
 * 
 * 
 * 
 * 
 * 
 * 
 * 
 * 
 * 
 * 
 * 
 * 
 * 
 * 
 * 
 * 
 * 
 * 
 * 
 * Feature name This is the name that will appear in the element's feature list as
 * produced by the toString() method or by calling
 * getAllFeatureNames
Expected type As features are represented as a Map connecting a
 * String and an Object then, in theory, a feature can
 * take any object as a value. This table entry defines the type that the
 * SimpleNLG system expects.
Created by Defines where the feature is created. In addition, all features can be
 * added specifically by users
Used by Defines which processors use the feature.
Applies to Defines which structural, syntactical or lexical elements this feature is
 * applied to.
Default Any default values attributed to the feature are given here.

 *
 * @author E. Reiter and D. Westwater, University of Aberdeen.
 * @version 4.0
 */

@SuppressWarnings("nls")
public abstract class LexicalFeature {

	/**
	 * 
	 * This feature is used to map an acronym element to the full forms of the
	 * acronym.
	 * 
	 * 
	 * 
	 * 
	 * 
	 * 
	 * 
	 * 
	 * 
	 * 
	 * 
	 * 
	 * 
	 * 
	 * 
	 * 
	 * 
	 * 
	 * 
	 * 
	 * 
	 * 
	 * 
	 * 
	 * 
	 * 
	 * Feature name acronymOf
Expected type List
Created by Lexicons that support acronyms should set this feature.
Used by No processors currently use this feature.
Applies to Any lexical item.
Default null
	 */
	public static final String ACRONYM_OF = "acronym_of";

	/**
	 * 
	 * This feature is used to map a word to its acronyms.
	 * 
	 * 
	 * 
	 * 
	 * 
	 * 
	 * 
	 * 
	 * 
	 * 
	 * 
	 * 
	 * 
	 * 
	 * 
	 * 
	 * 
	 * 
	 * 
	 * 
	 * 
	 * 
	 * 
	 * 
	 * 
	 * 
	 * Feature name acronyms
Expected type List
Created by Lexicons that support acronyms should set this feature.
Used by No processors currently use this feature.
Applies to Any lexical item.
Default null
	 */
	public static final String ACRONYMS = "acronyms";

	/*
	 *  This feature is used to list all the possible inflectional variants
	 * of a word. For example, the word fish can be both uncount
	 * (plural: fish) and reg (plural: fishes).  
	 * 
	 * 
	 * 
	 *   Feature name  infl
  Expected type List  
  Created
	 * by  Lexicons that support inflectional variants should set
	 * this feature.  
  Used by  No processors
	 * currently use this feature.  
  Applies to Any lexical item.  
  Default null  
 
	 */
	// public static final String INFLECTIONS = "infl";

	/**
	 * 
	 * This feature is used to specify, for a given word, what its default
	 * inflectional variant is, if more than one is possible.
	 * 
	 * 
	 * 
	 * 
	 * 
	 * 
	 * 
	 * 
	 * 
	 * 
	 * 
	 * 
	 * 
	 * 
	 * 
	 * 
	 * 
	 * 
	 * 
	 * 
	 * 
	 * 
	 * 
	 * 
	 * 
	 * 
	 * Feature name default_infl
Expected type Inflection
Created by Lexicons that support multiple inflectional variants should set this
	 * feature.
Used by {@link simplenlg.morphology.english.MorphologyProcessor}.
Applies to Nouns and verbs.
Default null
	 */
	public static final String DEFAULT_INFL = "default_infl";

	/**
	 * 
	 * This feature is used to specify the spelling variants of a word.
	 * 
	 * 
	 * 
	 * 
	 * 
	 * 
	 * 
	 * 
	 * 
	 * 
	 * 
	 * 
	 * 
	 * 
	 * 
	 * 
	 * 
	 * 
	 * 
	 * 
	 * 
	 * 
	 * 
	 * 
	 * 
	 * 
	 * Feature name spell_vars
Expected type List
Created by Lexicons that support multiple spelling variants should set this
	 * feature.
Used by No processors currently use this feature.
Applies to Any lexical item.
Default null
	 */
	public static final String SPELL_VARS = "spell_vars";

	/**
	 * 
	 * This feature is used to specify the default spelling variant of a word,
	 * if it has more than one.
	 * 
	 * 
	 * 
	 * 
	 * 
	 * 
	 * 
	 * 
	 * 
	 * 
	 * 
	 * 
	 * 
	 * 
	 * 
	 * 
	 * 
	 * 
	 * 
	 * 
	 * 
	 * 
	 * 
	 * 
	 * 
	 * 
	 * Feature name default_spell
Expected type String
Created by Lexicons that support multiple spelling variants should set this
	 * feature.
Used by {@link simplenlg.morphology.english.MorphologyProcessor}
Applies to Any lexical item.
Default null
	 */
	public static final String DEFAULT_SPELL = "default_spell";

	/**
	 * 
	 * This feature is used to define the base form for phrases and words.
	 * 
	 * 
	 * 
	 * 
	 * 
	 * 
	 * 
	 * 
	 * 
	 * 
	 * 
	 * 
	 * 
	 * 
	 * 
	 * 
	 * 
	 * 
	 * 
	 * 
	 * 
	 * 
	 * 
	 * 
	 * 
	 * 
	 * Feature name baseForm
Expected type String
Created by The lexicon accessor also creates the feature when looking up words
	 * in the lexicon. Sometimes the phrase factory sets this feature as well,
	 * as an approximate realisation for debuggin purposes
Used by The morphology processor uses the base form in its simple rules for
	 * determining word inflection. The morphology processor and syntax
	 * processor also use the base form for lexicon look ups if the base word
	 * has not been set. Base forms on phrases are purely to aid debugging.
Applies to Phrases and words.
Default null
	 */
	public static final String BASE_FORM    = "base_form";
	/**
	 * 
	 * This feature is used for determining the position of adjectives. Setting
	 * this value to true means that the adjective can occupy the
	 * classifying position.
	 * 
	 * 
	 * 
	 * 
	 * 
	 * 
	 * 
	 * 
	 * 
	 * 
	 * 
	 * 
	 * 
	 * 
	 * 
	 * 
	 * 
	 * 
	 * 
	 * 
	 * 
	 * 
	 * 
	 * 
	 * 
	 * 
	 * Feature name classifying
Expected type Boolean
Created by Any lexicon that supports adjective positioning.
Used by The syntax processor to determine the ordering of adjectives.
Applies to Adjectives within noun phrases.
Default Boolean.FALSE
	 */
	public static final String CLASSIFYING  = "classifying";
	/**
	 * 
	 * This feature is used for determining the position of adjectives. Setting
	 * this value to true means that the adjective can occupy the
	 * colour position.
	 * 
	 * 
	 * 
	 * 
	 * 
	 * 
	 * 
	 * 
	 * 
	 * 
	 * 
	 * 
	 * 
	 * 
	 * 
	 * 
	 * 
	 * 
	 * 
	 * 
	 * 
	 * 
	 * 
	 * 
	 * 
	 * 
	 * Feature name colour
Expected type Boolean
Created by Any lexicon that supports adjective positioning.
Used by The syntax processor to determine the ordering of adjectives.
Applies to Adjectives within noun phrases.
Default Boolean.FALSE
	 */
	public static final String COLOUR       = "colour";
	/**
	 * 
	 * This feature gives the comparative form for adjectives and adverbs. For
	 * example, dizzier is the comparative form of dizzy,
	 * fatter is the comparative form of fat and
	 * earlier is the comparative form of early.
	 * 
	 * 
	 * 
	 * 
	 * 
	 * 
	 * 
	 * 
	 * 
	 * 
	 * 
	 * 
	 * 
	 * 
	 * 
	 * 
	 * 
	 * 
	 * 
	 * 
	 * 
	 * 
	 * 
	 * 
	 * 
	 * 
	 * Feature name comparative
Expected type String
Created by Can be created automatically by the lexicon or added manually by
	 * users.
Used by The morphology processor uses this information to correctly inflect
	 * words.
Applies to Adjectives and adverbs only.
Default null
	 */
	public static final String COMPARATIVE  = "comparative";
	/**
	 * 
	 * This feature determines if a verb is ditransitive, meaning that it can
	 * have a subject, direct object and indirect object. For example in the
	 * phrase he gave Mary ten pounds, the verb give has three
	 * components: the subject is the person doing the giving (he), the
	 * direct object is the object being passed (ten pounds) and the
	 * indirect object is the recipient (Mary).
	 * 
	 * 
	 * 
	 * 
	 * 
	 * 
	 * 
	 * 
	 * 
	 * 
	 * 
	 * 
	 * 
	 * 
	 * 
	 * 
	 * 
	 * 
	 * 
	 * 
	 * 
	 * 
	 * 
	 * 
	 * 
	 * 
	 * Feature name ditransitive
Expected type Boolean
Created by The feature is set by the lexicon if it supports the recording of the
	 * transitive nature of verbs.
Used by The ditransitive value is currently not used.
Applies to Verbs only.
Default Boolean.FALSE
	 */
	public static final String DITRANSITIVE = "ditransitive";
	/**
	 * 
	 * This feature determines whether a noun is masculine, feminine or neuter
	 * in nature.
	 * 
	 * 
	 * 
	 * 
	 * 
	 * 
	 * 
	 * 
	 * 
	 * 
	 * 
	 * 
	 * 
	 * 
	 * 
	 * 
	 * 
	 * 
	 * 
	 * 
	 * 
	 * 
	 * 
	 * 
	 * 
	 * 
	 * Feature name gender
Expected type Gender
Created by The phrase factory creates the gender of pronouns when creating
	 * phrases and on all nouns within a noun phrase.
Used by The syntax processor ensures that the head noun in a noun phrase has
	 * a gender matching that applied to the phrase as a whole. The morphology
	 * processor uses gender to determine the appropriate form for pronouns and
	 * for setting the form of some verbs.
Applies to Specifically it applies to nouns and pronouns but the feature is also
	 * written to noun phrases and verbs.
Default Gender.NEUTER
	 */
	public static final String GENDER       = "gender";
	/**
	 * 
	 * This flag determines if an adverb is an intensifier, such as
	 * very.
	 * 
	 * 
	 * 
	 * 
	 * 
	 * 
	 * 
	 * 
	 * 
	 * 
	 * 
	 * 
	 * 
	 * 
	 * 
	 * 
	 * 
	 * 
	 * 
	 * 
	 * 
	 * 
	 * 
	 * 
	 * 
	 * 
	 * Feature name intensifier
Expected type Boolean
Created by The information is read from Lexicons that support this feature.
Used by Currently not used.
Applies to Adverbs only.
Default Boolean.FALSE.
	 */
	public static final String INTENSIFIER  = "intensifier";
	/**
	 * 
	 * This flag highlights a verb that can only take a subject and no objects.
	 * 
	 * 
	 * 
	 * 
	 * 
	 * 
	 * 
	 * 
	 * 
	 * 
	 * 
	 * 
	 * 
	 * 
	 * 
	 * 
	 * 
	 * 
	 * 
	 * 
	 * 
	 * 
	 * 
	 * 
	 * 
	 * 
	 * Feature name intransitive
Expected type Boolean
Created by The information is read from Lexicons that support this feature.
Used by Currently not used.
Applies to Verbs only.
Default Boolean.FALSE.
	 */
	public static final String INTRANSITIVE = "intransitive";

	/*
	 *  This feature represents non-countable nouns such as mud,
	 * sand and water.  
	 * 
	 * 
	 * 
	 * 
	 *  Feature name  nonCount  
 Expected type  Boolean  
 Created by  Supporting lexicons.  
 Used by  The morphology processor will not pluralise
	 * non-countable nouns.  
  Applies to  Nouns
	 * only.  
  Default Boolean.FALSE.  
 
	 */
	// public static final String NON_COUNT = "nonCount";

	/**
	 * 
	 * This feature gives the past tense form of a verb. For example, the past
	 * tense of eat is ate, the past tense of walk is
	 * walked.
	 * 
	 * 
	 * 
	 * 
	 * 
	 * 
	 * 
	 * 
	 * 
	 * 
	 * 
	 * 
	 * 
	 * 
	 * 
	 * 
	 * 
	 * 
	 * 
	 * 
	 * 
	 * 
	 * 
	 * 
	 * 
	 * 
	 * Feature name past
Expected type String
Created by All supporting lexicons but can be set by the user for irregular
	 * cases.
Used by The morphology processor uses this feature to correctly inflect
	 * verbs. This feature will be looked at first before any reference to
	 * lexicons or morphology rules.
Applies to Verbs and verb phrases only.
Default null.
	 */
	public static final String PAST               = "past";
	/**
	 * 
	 * This feature gives the past participle tense form of a verb. For many
	 * verbs the past participle is exactly the same as the past tense, for
	 * example, the verbs talk, walk and say have
	 * past tense and past participles of talked, walked and
	 * said. Contrast this with the verbs do, eat and
	 * sing. The past tense of these verbs is did,
	 * ate and sang respectively. while the respective past
	 * participles are done, eaten and sung
	 * 
	 * 
	 * 
	 * 
	 * 
	 * 
	 * 
	 * 
	 * 
	 * 
	 * 
	 * 
	 * 
	 * 
	 * 
	 * 
	 * 
	 * 
	 * 
	 * 
	 * 
	 * 
	 * 
	 * 
	 * 
	 * 
	 * Feature name pastParticiple
Expected type String
Created by All supporting lexicons but can be set by the user for irregular
	 * cases.
Used by The morphology processor uses this feature to correctly inflect
	 * verbs. This feature will be looked at first before any reference to
	 * lexicons or morphology rules.
Applies to Verbs and verb phrases only.
Default null.
	 */
	public static final String PAST_PARTICIPLE    = "pastParticiple";
	/**
	 * 
	 * This feature gives the plural form of a noun. For example, the plural of
	 * dog is dogs and the plural of sheep is
	 * sheep.
	 * 
	 * 
	 * 
	 * 
	 * 
	 * 
	 * 
	 * 
	 * 
	 * 
	 * 
	 * 
	 * 
	 * 
	 * 
	 * 
	 * 
	 * 
	 * 
	 * 
	 * 
	 * 
	 * 
	 * 
	 * 
	 * 
	 * Feature name plural
Expected type String
Created by All supporting lexicons but can be set by the user for irregular
	 * cases.
Used by The morphology processor uses this feature to correctly inflect
	 * plural nouns. This feature will be looked at first before any reference
	 * to lexicons or morphology rules.
Applies to Nouns only.
Default null.
	 */
	public static final String PLURAL             = "plural";
	/**
	 * 
	 * This flag is set on adjectives that can also be used as a predicate. For
	 * example happy.
	 * 
	 * 
	 * 
	 * 
	 * 
	 * 
	 * 
	 * 
	 * 
	 * 
	 * 
	 * 
	 * 
	 * 
	 * 
	 * 
	 * 
	 * 
	 * 
	 * 
	 * 
	 * 
	 * 
	 * 
	 * 
	 * 
	 * Feature name predicative
Expected type Boolean
Created by Any supporting lexicon.
Used by Currently not used.
Applies to Adjectives only.
Default Boolean.FALSE.
	 */
	public static final String PREDICATIVE        = "predicative";
	/**
	 * 
	 * This feature gives the present participle form of a verb. For example,
	 * the present participle form of eat is eating and the
	 * present participle form of walk is walking.
	 * 
	 * 
	 * 
	 * 
	 * 
	 * 
	 * 
	 * 
	 * 
	 * 
	 * 
	 * 
	 * 
	 * 
	 * 
	 * 
	 * 
	 * 
	 * 
	 * 
	 * 
	 * 
	 * 
	 * 
	 * 
	 * 
	 * Feature name presentParticiple
Expected type String
Created by All supporting lexicons but can be set by the user for irregular
	 * cases.
Used by The morphology processor uses this feature to correctly inflect
	 * verbs. This feature will be looked at first before any reference to
	 * lexicons or morphology rules.
Applies to Verbs only.
Default null.
	 */
	public static final String PRESENT_PARTICIPLE = "presentParticiple";
	/**
	 * 
	 * This feature gives the present third person singular form of a verb. For
	 * example, the present participle form of eat is eats as
	 * in the dog eats. Another example is ran being the
	 * present third person singular form of run as in
	 * John ran home.
	 * 
	 * 
	 * 
	 * 
	 * 
	 * 
	 * 
	 * 
	 * 
	 * 
	 * 
	 * 
	 * 
	 * 
	 * 
	 * 
	 * 
	 * 
	 * 
	 * 
	 * 
	 * 
	 * 
	 * 
	 * 
	 * 
	 * Feature name present3s
Expected type String
Created by All supporting lexicons but can be set by the user for irregular
	 * cases.
Used by The morphology processor uses this feature to correctly inflect
	 * verbs. This feature will be looked at first before any reference to
	 * lexicons or morphology rules.
Applies to Verbs only.
Default null.
	 */
	public static final String PRESENT3S          = "present3s";
	/**
	 * 
	 * This flag is used to determine whether a noun is a proper noun, such as a
	 * person's name.
	 * 
	 * 
	 * 
	 * 
	 * 
	 * 
	 * 
	 * 
	 * 
	 * 
	 * 
	 * 
	 * 
	 * 
	 * 
	 * 
	 * 
	 * 
	 * 
	 * 
	 * 
	 * 
	 * 
	 * 
	 * 
	 * 
	 * Feature name proper
Expected type Boolean
Created by Can be set by supporting lexicons or by the user.
Used by The morphology processor will not pluralise proper nouns.
Applies to Nouns only.
Default Boolean.FALSE.
	 */
	public static final String PROPER             = "proper";
	/**
	 * 
	 * This feature is used for determining the position of adjectives. Setting
	 * this value to true means that the adjective can occupy the
	 * qualitative position.
	 * 
	 * 
	 * 
	 * 
	 * 
	 * 
	 * 
	 * 
	 * 
	 * 
	 * 
	 * 
	 * 
	 * 
	 * 
	 * 
	 * 
	 * 
	 * 
	 * 
	 * 
	 * 
	 * 
	 * 
	 * 
	 * 
	 * Feature name qualitative
Expected type Boolean
Created by Any lexicon that supports adjective positioning.
Used by The syntax processor to determine the ordering of adjectives.
Applies to Adjectives within noun phrases.
Default Boolean.FALSE
	 */
	public static final String QUALITATIVE        = "qualitative";
	/**
	 * 
	 * This flag is set if a pronoun is written in the reflexive form. For
	 * example, myself, yourself, ourselves.
	 * 
	 * 
	 * 
	 * 
	 * 
	 * 
	 * 
	 * 
	 * 
	 * 
	 * 
	 * 
	 * 
	 * 
	 * 
	 * 
	 * 
	 * 
	 * 
	 * 
	 * 
	 * 
	 * 
	 * 
	 * 
	 * 
	 * Feature name isReflexive
Expected type Boolean
Created by The phrase factory will recognise personal pronouns in reflexive
	 * form.
Used by The morphology processor will correctly inflect reflexive pronouns.
Applies to Pronouns only.
Default Boolean.FALSE
	 */
	public static final String REFLEXIVE          = "reflexive";
	/**
	 * 
	 * This feature is used to define whether an adverb can be used as a clause
	 * modifier, which are normally applied at the beginning of clauses. For
	 * example, unfortunately.
	 * 
	 * 
	 * 
	 * 
	 * 
	 * 
	 * 
	 * 
	 * 
	 * 
	 * 
	 * 
	 * 
	 * 
	 * 
	 * 
	 * 
	 * 
	 * 
	 * 
	 * 
	 * 
	 * 
	 * 
	 * 
	 * 
	 * Feature name sentenceModifier
Expected type Boolean
Created by Any lexicon that supports this feature.
Used by generic addModifier methods, to decide where to put an adverb
Applies to Adverbs only.
Default Boolean.FALSE
	 */
	public static final String SENTENCE_MODIFIER  = "sentence_modifier";
	/**
	 * 
	 * This feature gives the superlative form for adjectives and adverbs. For
	 * example, fattest is the superlative form of fat and
	 * earliest is the superlative form of early.
	 * 
	 * 
	 * 
	 * 
	 * 
	 * 
	 * 
	 * 
	 * 
	 * 
	 * 
	 * 
	 * 
	 * 
	 * 
	 * 
	 * 
	 * 
	 * 
	 * 
	 * 
	 * 
	 * 
	 * 
	 * 
	 * 
	 * Feature name superlative
Expected type String
Created by Can be created automatically by the lexicon or added manually by
	 * users.
Used by The morphology processor uses this information to correctly inflect
	 * words.
Applies to Adjectives and adverbs only.
Default null
	 */
	public static final String SUPERLATIVE        = "superlative";
	/**
	 * 
	 * This flag highlights a verb that can only take a subject and an object.
	 * 
	 * 
	 * 
	 * 
	 * 
	 * 
	 * 
	 * 
	 * 
	 * 
	 * 
	 * 
	 * 
	 * 
	 * 
	 * 
	 * 
	 * 
	 * 
	 * 
	 * 
	 * 
	 * 
	 * 
	 * 
	 * 
	 * Feature name transitive
Expected type Boolean
Created by Any lexicon supporting this feature.
Used by Currently not used.
Applies to Verbs only.
Default Boolean.FALSE.
	 */
	public static final String TRANSITIVE         = "transitive";

	/**
	 * 
	 * This feature is used to define whether an adverb can be used as a verb
	 * modifier, which are normally added in a phrase before the verb itself.
	 * For example, quickly.
	 * 
	 * 
	 * 
	 * 
	 * 
	 * 
	 * 
	 * 
	 * 
	 * 
	 * 
	 * 
	 * 
	 * 
	 * 
	 * 
	 * 
	 * 
	 * 
	 * 
	 * 
	 * 
	 * 
	 * 
	 * 
	 * 
	 * Feature name verbModifier
Expected type Boolean
Created by Any lexicon that supports this feature.
Used by generic addModifier methods, to decide where to put an adverb.
Applies to Adverbs only.
Default Boolean.FALSE
	 */
	public static final String VERB_MODIFIER = "verb_modifier";

	/**
	 * 
	 * This feature determines if the pronoun is an expletive or not. Expletive
	 * pronouns are usually it or there in sentences such as:

	 * It is raining now.

	 * There are ten desks in the room.
	 * 
	 * 
	 * 
	 * 
	 * 
	 * 
	 * 
	 * 
	 * 
	 * 
	 * 
	 * 
	 * 
	 * 
	 * 
	 * 
	 * 
	 * 
	 * 
	 * 
	 * 
	 * 
	 * 
	 * 
	 * 
	 * 
	 * Feature name isExpletive
Expected type Boolean
Created by The feature needs to be set by the user.
Used by The syntax processor uses the expletive on verb phrases for
	 * determining the correct number agreement.
Applies to Certain pronouns when used as subjects of verb phrases.
Default Boolean.FALSE
	 */
	public static final String EXPLETIVE_SUBJECT = "expletive_subject";

	/**
	 * The constructor is never needed.
	 */
	private LexicalFeature() {
		// do nothing
	}

	/**
	 * Return those features related to a word's inflection, depending on its
	 * category, that is, the constants for
	 * PAST, PAST_PARTICIPLE, PLURAl, PRESENT_PARTICIPLE, PRESENT3S, COMPARATIVE
	 * or SUPERLATIVE.
	 *
	 * @param cat the category
	 * @return the inflectional feature names
	 */
	public static String[] getInflectionalFeatures(ElementCategory cat) {
		if(PhraseCategory.NOUN_PHRASE.equals(cat) || LexicalCategory.NOUN.equals(cat))
			return new String[]{PLURAL};
		else if(PhraseCategory.VERB_PHRASE.equals(cat) || LexicalCategory.VERB.equals(cat))
			return new String[]{PAST, PAST_PARTICIPLE, PRESENT_PARTICIPLE, PRESENT3S};
		else if(PhraseCategory.ADJECTIVE_PHRASE.equals(cat) || LexicalCategory.ADJECTIVE.equals(cat))
			return new String[]{COMPARATIVE, SUPERLATIVE};
		else
			return null;

	}
}

Feature name	This is the name that will appear in the element's feature list as * produced by the `toString()` method or by calling * `getAllFeatureNames`
Expected type	As features are represented as a `Map` connecting a * `String` and an `Object` then, in theory, a feature can * take any object as a value. This table entry defines the type that the * SimpleNLG system expects.
Created by	Defines where the feature is created. In addition, all features can be * added specifically by users
Used by	Defines which processors use the feature.
Applies to	Defines which structural, syntactical or lexical elements this feature is * applied to.
Default	Any default values attributed to the feature are given here.

Feature name	acronymOf
Expected type	`List`
Created by	Lexicons that support acronyms should set this feature.
Used by	No processors currently use this feature.
Applies to	Any lexical item.
Default	`null`

Feature name	acronyms
Expected type	`List`
Created by	Lexicons that support acronyms should set this feature.
Used by	No processors currently use this feature.
Applies to	Any lexical item.
Default	`null`

Feature name	infl
Expected type	`List`
*Created by**	Lexicons that support inflectional variants should set * this feature.
Used by	No processors * currently use this feature.
Applies to	Any lexical item.
Default	`null`

Feature name	default_infl
Expected type	`Inflection`
Created by	Lexicons that support multiple inflectional variants should set this * feature.
Used by	{@link simplenlg.morphology.english.MorphologyProcessor}.
Applies to	Nouns and verbs.
Default	`null`

Feature name	spell_vars
Expected type	`List`
Created by	Lexicons that support multiple spelling variants should set this * feature.
Used by	No processors currently use this feature.
Applies to	Any lexical item.
Default	`null`

Feature name	default_spell
Expected type	`String`
Created by	Lexicons that support multiple spelling variants should set this * feature.
Used by	{@link simplenlg.morphology.english.MorphologyProcessor}
Applies to	Any lexical item.
Default	`null`

Feature name	baseForm
Expected type	`String`
Created by	The lexicon accessor also creates the feature when looking up words * in the lexicon. Sometimes the phrase factory sets this feature as well, * as an approximate realisation for debuggin purposes
Used by	The morphology processor uses the base form in its simple rules for * determining word inflection. The morphology processor and syntax * processor also use the base form for lexicon look ups if the base word * has not been set. Base forms on phrases are purely to aid debugging.
Applies to	Phrases and words.
Default	`null`

Feature name	classifying
Expected type	`Boolean`
Created by	Any lexicon that supports adjective positioning.
Used by	The syntax processor to determine the ordering of adjectives.
Applies to	Adjectives within noun phrases.
Default	`Boolean.FALSE`

Feature name	colour
Expected type	`Boolean`
Created by	Any lexicon that supports adjective positioning.
Used by	The syntax processor to determine the ordering of adjectives.
Applies to	Adjectives within noun phrases.
Default	`Boolean.FALSE`

Feature name	comparative
Expected type	`String`
Created by	Can be created automatically by the lexicon or added manually by * users.
Used by	The morphology processor uses this information to correctly inflect * words.
Applies to	Adjectives and adverbs only.
Default	`null`

Feature name	ditransitive
Expected type	`Boolean`
Created by	The feature is set by the lexicon if it supports the recording of the * transitive nature of verbs.
Used by	The ditransitive value is currently not used.
Applies to	Verbs only.
Default	`Boolean.FALSE`

Feature name	gender
Expected type	`Gender`
Created by	The phrase factory creates the gender of pronouns when creating * phrases and on all nouns within a noun phrase.
Used by	The syntax processor ensures that the head noun in a noun phrase has * a gender matching that applied to the phrase as a whole. The morphology * processor uses gender to determine the appropriate form for pronouns and * for setting the form of some verbs.
Applies to	Specifically it applies to nouns and pronouns but the feature is also * written to noun phrases and verbs.
Default	`Gender.NEUTER`

Feature name	intensifier
Expected type	`Boolean`
Created by	The information is read from Lexicons that support this feature.
Used by	Currently not used.
Applies to	Adverbs only.
Default	`Boolean.FALSE`.

Feature name	intransitive
Expected type	`Boolean`
Created by	The information is read from Lexicons that support this feature.
Used by	Currently not used.
Applies to	Verbs only.
Default	`Boolean.FALSE`.

Feature name	nonCount
Expected type	`Boolean`
Created by	Supporting lexicons.
Used by	The morphology processor will not pluralise * non-countable nouns.
Applies to	Nouns * only.
Default	`Boolean.FALSE`.

Feature name	past
Expected type	`String`
Created by	All supporting lexicons but can be set by the user for irregular * cases.
Used by	The morphology processor uses this feature to correctly inflect * verbs. This feature will be looked at first before any reference to * lexicons or morphology rules.
Applies to	Verbs and verb phrases only.
Default	`null`.

Feature name	pastParticiple
Expected type	`String`
Created by	All supporting lexicons but can be set by the user for irregular * cases.
Used by	The morphology processor uses this feature to correctly inflect * verbs. This feature will be looked at first before any reference to * lexicons or morphology rules.
Applies to	Verbs and verb phrases only.
Default	`null`.

Feature name	plural
Expected type	`String`
Created by	All supporting lexicons but can be set by the user for irregular * cases.
Used by	The morphology processor uses this feature to correctly inflect * plural nouns. This feature will be looked at first before any reference * to lexicons or morphology rules.
Applies to	Nouns only.
Default	`null`.

Feature name	predicative
Expected type	`Boolean`
Created by	Any supporting lexicon.
Used by	Currently not used.
Applies to	Adjectives only.
Default	`Boolean.FALSE`.

Feature name	presentParticiple
Expected type	`String`
Created by	All supporting lexicons but can be set by the user for irregular * cases.
Used by	The morphology processor uses this feature to correctly inflect * verbs. This feature will be looked at first before any reference to * lexicons or morphology rules.
Applies to	Verbs only.
Default	`null`.

Feature name	present3s
Expected type	`String`
Created by	All supporting lexicons but can be set by the user for irregular * cases.
Used by	The morphology processor uses this feature to correctly inflect * verbs. This feature will be looked at first before any reference to * lexicons or morphology rules.
Applies to	Verbs only.
Default	`null`.

Feature name	proper
Expected type	`Boolean`
Created by	Can be set by supporting lexicons or by the user.
Used by	The morphology processor will not pluralise proper nouns.
Applies to	Nouns only.
Default	`Boolean.FALSE`.

Feature name	qualitative
Expected type	`Boolean`
Created by	Any lexicon that supports adjective positioning.
Used by	The syntax processor to determine the ordering of adjectives.
Applies to	Adjectives within noun phrases.
Default	`Boolean.FALSE`

Feature name	isReflexive
Expected type	`Boolean`
Created by	The phrase factory will recognise personal pronouns in reflexive * form.
Used by	The morphology processor will correctly inflect reflexive pronouns.
Applies to	Pronouns only.
Default	`Boolean.FALSE`

Feature name	sentenceModifier
Expected type	`Boolean`
Created by	Any lexicon that supports this feature.
Used by	generic addModifier methods, to decide where to put an adverb
Applies to	Adverbs only.
Default	`Boolean.FALSE`

Feature name	superlative
Expected type	`String`
Created by	Can be created automatically by the lexicon or added manually by * users.
Used by	The morphology processor uses this information to correctly inflect * words.
Applies to	Adjectives and adverbs only.
Default	`null`

Feature name	transitive
Expected type	`Boolean`
Created by	Any lexicon supporting this feature.
Used by	Currently not used.
Applies to	Verbs only.
Default	`Boolean.FALSE`.

Feature name	verbModifier
Expected type	`Boolean`
Created by	Any lexicon that supports this feature.
Used by	generic addModifier methods, to decide where to put an adverb.
Applies to	Adverbs only.
Default	`Boolean.FALSE`

Feature name	isExpletive
Expected type	`Boolean`
Created by	The feature needs to be set by the user.
Used by	The syntax processor uses the expletive on verb phrases for * determining the correct number agreement.
Applies to	Certain pronouns when used as subjects of verb phrases.
Default	`Boolean.FALSE`