A-rule

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'''A-rule''' (affixation rule) is the formalism used for generating affixes in the UNLarium framework.
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'''A-rule''' (affixation rule) is the formalism used for generating affixes (prefixes, suffixes, infixes) in the UNLarium framework.  
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== Generative and enumerative lexica ==
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The repertoire of lexemes of a given language can be organized in two basic ways: 1) as a simple listing of all word forms, i.e., of all variants of the same lexeme ("die", "dies", "died", "dying", etc); or 2) as a list of base forms accompanied by morphological rules for generating their inflections ("die", +s, +d, etc). The first architecture, the "enumerative" one, states that a word form can be more accurately retrieved as a single atomic entity instead of as a combination of several different morphemes. Its main advantages concern word matching (faster and more precise as there is no possibility of over-generation) and construction (it is easier and often less expensive to list the irregular forms instead of trying to define paradigms for them). Nevertheless, the latter architecture, i.e., the "generative" one, which relies on the principle that “the smaller the better”, is far much more common, as its main advantages concern access (the word retrieval process is supposed to be faster), storage (it requires a smaller amount of memory space) and maintenance (changes are automatically propagated to all instances of a given entry).
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The UNLarium is mainly a generative environment, in the sense that word forms are expected to be represented by their corresponding LRUs and base forms, along with rules for generating their possible inflections. These are the '''m-rules''', to be provided either as LRU-specific (in case of irregular behaviour) or as inflectional paradigms (applying to several different LRUs).
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== When to use a-rules ==
 
== When to use a-rules ==
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A-rules are used for prefixation, suffixation and infixation, i.e., for morphological changes affecting a given base form. They are mainly used for generating '''inflections''' (such as "book">"books", "love">"loved") or '''derivations''' (such as "dress">"undress", "write">"writer", "give">"give in" . They may also be used for generating some internal phonetic changes due to morphological behaviour, such as metaphony ("foot">"feet").
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A-rules are used for prefixation, suffixation and infixation, i.e., for adding morphemes to a given base form. They are used for generating '''inflections''' (such as "book">"books", "love">"loved") or '''derivations''' (such as "dress">"undress", "write">"writer").  
 
== When not to use a-rules ==
 
== When not to use a-rules ==
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A-rules are not to be used for phonetic changes occurring at word boundaries (such as "a" > "an" in "a book" > "an arm") or for syntactic changes (such as the insertion of new words in compound tenses: "go" > "have gone").  
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A-rules are not to be used for '''composition''' (i.e., to form new words by combining or putting together old words, as in "give">"give in", "go">"have gone" or "man">"fireman").  
 
== Types of a-rules ==
 
== Types of a-rules ==
 
There are two types of a-rules:
 
There are two types of a-rules:

Revision as of 09:57, 25 January 2010

A-rule (affixation rule) is the formalism used for generating affixes (prefixes, suffixes, infixes) in the UNLarium framework.

Contents

When to use a-rules

A-rules are used for prefixation, suffixation and infixation, i.e., for adding morphemes to a given base form. They are used for generating inflections (such as "book">"books", "love">"loved") or derivations (such as "dress">"undress", "write">"writer").

When not to use a-rules

A-rules are not to be used for composition (i.e., to form new words by combining or putting together old words, as in "give">"give in", "go">"have gone" or "man">"fireman").

Types of a-rules

There are two types of a-rules:

  • simple a-rules involve a single action (such as prefixation, suffixation or infixation); and
  • complex a-rules involve more than one action (such as circumfixation).

Simple a-rules

There are three types of simple a-rules:

  • prefixation, for adding morphemes at the beginning of a base form
  • suffixation, for adding morphemes at the end of a base form
  • infixation, for changing the internal structure of a base form

Syntax

The syntax for simple a-rules is the following:

prefixation 

CONDITION := “ADDED” < “DELETED”;

suffixation 

CONDITION := “DELETED” > “ADDED”;

infixation 

 CONDITION := “DELETED” : “ADDED”;

Where:

  • CONDITION = tag (such as “PLR”, “FEM”, etc) or list of tags (“FEM&PLR”) that indicates when the rule should be applied
  • ADDED = the string to be added (between quotes);
  • DELETED = the string to be deleted (between quotes);

Examples

Prefixation
RULE BEHAVIOR BEFORE AFTER
X:=”y”<”z”; if X replace the string “z” by the string “y” in the beginning of the string zabc yabc
X:=”y”<1; if X replace the first character of the string by “y” zabc yabc
X:=”y”<0; if X add the string “y” to the beginning of the string zabc yzabc
X:=”y”<; if X add the string “y” to the beginning of the string (idem previous) zabc yzabc
X:=”y”<<0; if X add the string “y” and a blank space to the beginning of the string zabc y zabc
X:=”y”<<; if X add the string “y” and a blank space to the beginning of the string (idem previous) zabc y zabc


Suffixation
RULE BEHAVIOR BEFORE AFTER
X:=”z”>”y”; if X replace the string “z” by the string “y” in the end of the string abcz abcy
X:=1>”y”; if X replace the last character of the string by “y” abcz abcy
X:=0>”y”; if X add the string “y” to the end of the string abcz abczy
X:=>”y”; if X add the string “y” to the end of the string (idem previous) abcz abczy
X:=0>>”y”; if X add a blank space and the string “y” to the end of the string abcz abcz y
X:=>>”y”; if X add a blank space and the string “y” to the end of the string (idem previous) abcz abcz y


Infixation
RULE BEHAVIOR BEFORE AFTER
X:=”y”; if X replace the whole by “y” X y
X:=”z”:”y”; if X replace the string “z” by “y” azbc aybc
X:=[2;3]:”y”; if X replace the second to the third character by “z” abcz ayz
X:=Y; replace the feature X by the feature Y X Y

Observations

Rules will only be applied if all conditions are true
X:=”y”<”z”; ( “zabc” changes to “yabc”, but “abc” remains “abc” since there is no "z" to be replaced)
Each action is applied only once (i.e, rules are not exhaustive)
PLR:=0>”s”; ("X" becomes "Xs", and not "Xssssss...")
The replacement rule applies only once to the same string
X:=”a”:”b”; ( “aaa” becomes “baa” and not “bbb”)
In prefixation and suffixation rules, the part to be deleted may be represented by the number of characters (without quotes)
PLR := “X”<””; = PLR := “X”<0; (ABC becomes XABC)
PLR:= “X”<”A”; = PLR:= “X”<1; (ABC becomes XBC)
PLR:= “XY”<”AB”; = PLR:= “XY”<2; (ABC becomes XYC)
PLR:=””>”X”; = PLR:= 0>”X”; (ABC becomes ABCX)
PLR:=”C”>”X”; = PLR:= 1>”X”; (ABC becomes ABX)
PLR:=”BC”>”XY”; = PLR:= 2>”XY”; (ABC becomes AXY)
In replacement rules, the part to be deleted may be omitted if the whole string is to be replaced
PLR:=”ABC”:”XYZ”; = PLR:=”XYZ” (ABC becomes XYZ)
In replacement rules, the part to be deleted may be represented by an interval of characters in the format [beginning-end]
PLR:=”B”:”X”; = PLR:=[2-2]:”X”; (ABC becomes AXC)
The symbol “^” is used for negation (“^MCL” means “not MCL”)
NOU&^MCL:=”x”:”y”; (If NOU and not MCL then replace “x” by “y”)
“<<” and “>>” add blank spaces
X:=”a”<<”b” (“bc” becomes “a bc” and not “abc”)

Common mistakes

  • nou:= ”y”<”z”; (WRONG: Tags are case sensitive)
  • NNN:= ”y”<”z”; (WRONG: NNN is not defined in the tagset)
  • NOUFEM:=”y”<”z”; (WRONG: Tags must be separated by “&”)
  • NOU,FEM:=”y”<”z”; (WRONG: Tags must be separated by “&”)
  • NOU & FEM:=”y”<”z”; (WRONG: There can be no blank spaces between tags)
  • X:=1<1; (WRONG: The left side must always be a string in a prefixation rule)
  • X:=1>1; (WRONG: The right side must always be a string in a suffixation rule)
  • X:=1; (WRONG: Replacement rules do not allow for numbers)
  • X:=1:1; (WRONG: Replacement rules do not allow for numbers)

Complex a-rules

Complex a-rules are formed from the combination of simple a-rules:

  • circumfixation (prefixation + suffixation), to add a prefix and a suffix at the same time
  • prefixation + infixation, to add a prefix and a suffix at the same time
  • infixation + suffixation, to add an infix and a suffix at the same time
  • prefixation + infixation + suffixation, to add a prefix, an infix and a suffix at the same time

Syntax

Complex a-rules are formed by concatenating simple a-rules with ",":

circumfixation 

CONDITION := “ADDED” < “DELETED” , "DELETED" > "ADDED";

prefixation + infixation 

CONDITION := “ADDED” < “DELETED” , "DELETED" : "ADDED";

infixation + suffixation 

CONDITION := "DELETED" : "ADDED" , "DELETED" > "ADDED";

prefixation + infixation + suffixation 

CONDITION := “ADDED” < “DELETED” , "DELETED" : "ADDED" , "DELETED" > "ADDED";

Examples

Complex m-rules
RULE BEHAVIOR BEFORE AFTER
X:=”x”<0, 0>"y"; if X add "x" to the beginning and "z" to the end of the string A xAy
X:=”x”<0, "A":"y"; if X add "x" to the beginning and replace "A" by "y" ABC xyBC
X:="A":"y", 0>"x"; if X replace "A" by "y" and add "x" to the end of the string ABC yBCx
X:=”x”<0, "A":"y", 0>"z"; if X add "x" to the beginning, replace "A" by "y" and add "z" to the end of the string ABC xyBCz

Observations

Complex a-rules are also used to integrate different simple a-rules
ORD:="1">"1st";
ORD:="2">"2nd";
ORD:="3">"3rd"; 		ORD:="1">"1st", "2">"2nd", "3">"3rd";
Actions are applied from left to right (i.e., order is important)
PLR := "s" > "ses", "y" > "ies"; (kiss > kisses, city > cities)
PLR := "y" > "ies", "s" > "ses"; (kiss > kisses, city>cities>citieses)

Formal syntax for a-rules

A-rules comply with the following syntax: 

<A-RULE>           ::= <CONDITION> “:=” <ACTION> [, <ACTION>]* “;”
<CONDITION>        ::= <ATAG>[“&”[“^”]<ATAG>]*
<ATAG>             ::= {one of the tags defined in the UNDLF Tagset}
<ACTION>           ::= <LEFT APPENDING> | <RIGHT APPENDING> | <REPLACEMENT>
<LEFT APPENDING>   ::= <ADDED>	 {“<” | “<<”} 	[ <DELETED> ]
<RIGHT APPENDING>  ::= [ <DELETED> ]	 {“>” | “>>”} 	<ADDED>
<REPLACEMENT>      ::= [ <STRING> ":" ] <ADDED> | "[" <INTEGER> "-" <INTEGER> "]" ":"  <ADDED>
<ADDED>            ::= <STRING> 
<DELETED>          ::= <STRING> | <INTEGER>  
<STRING>           ::= “ “ “ [a..Z]+ “ “ “
<INTEGER>          ::= [0..9]+

where

<a> = a is a non-terminal symbol
“a“ = a is a constant
[a] = a can be omitted
a | b = a or b
{ a | b } = either a or b
a* = a can be repeated 0 or more times
a+ = a can be repeated 1 or more times

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