A-rule

M-rule is the formalism used for describing morphological behavior in the UNL framework. It is used in inflectional paradigms, in inflectional rules, in attribute rules and in morphological settings.

Syntax

A M-rule rule should comply with the following syntax:

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

Examples

Left appending (prefixation) rules

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

Right appending (suffixation) rules

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

Replacement (infixation) rules

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

The symbol “^” can be used for negation (“^MCL” means “not MCL”)

NOU&^MCL:=”x”:”y”; (If NOU and not MCL then replace “x” by “y”)

Rules will only be applied if all conditions are true

X:=”y”<”z”; ( “zabc” changes to “yabc”, but “abc” remains “abc”)

There can be as many rules as necessary, but they will always be applied from left to right.

X:=”y”<”z”,”a”<”y”; (“zabc” > “yabc” > “aabc”)

The replacement rule applies only once the same action

X:=”a”:”b”; ( “aaa” becomes “baa” and not “bbb”)

“<<” 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 left appending rule)
• X:=1>1; (WRONG: The right side must always be a string in a right appending rule)
• X:=1; (WRONG: Replacement rules do not allow for numbers)
• X:=1:1; (WRONG: Replacement rules do not allow for numbers)