Tutorial Pattern Matching

Pattern Matching

You can build a lot of simple questions and answers with this form, but it becomes unmanageable when you get to very large numbers. You end up repeating yourself and trying to guess every possible combination of a question someone might ask.

To solve this problem AIML comes with power pattern matching capabilities. Instead of including every possible world in every possible combination, an AIML developer uses special syntax which can be used to match one or more words. This allows the AIML developer to focus on the core aspects of the question.

The purpose of this is to allow the developer to ignore the unimportant parts of the question and focus only on the core aspects. As with most languages there many different ways to ask the question, but most are just variations on a core theme. This is where pattern matching helps.

These matching operators are

• Priority. Matches the exact word specified by proceeding the word with a $
• 0 or more. Matches 0 or more words in a sequence. Can be either # or ^ depending upon precedence preference
• 1 or more. Matches 1 or more words in a sequence. Can be either _ or * depending upon precedence preference
• Sets. Matches a word as a member of a specific set. Sets are files of words, each file contains one set, such as colours or numbers.
• ISet. Similar to sets but, but the members are contained inline to the AIML
• Bot. Matches a word again a bot predicate, such as bot name, age, location etc
• Regex. Matches a one-word regular expression

For more information on pattern matching and operator, precedence see Pattern Matching

0 or More Matching

The special characters # or ^ where added in AIML 2.0 and mean matching zero or more words before either the next specific match or the end of the sentence.

For example HELLO # would match any sentence that starts with the word HELLO and has zero or more words.

<?xml version="1.0" encoding="UTF-8"?>
<aiml version="2.0">
    <category>
        <pattern>HELLO #</pattern>
        <template>Hi there!</template>
    <category>
</aiml>

1 or More Matching

The special characters _ or * are used to match one of more words after the specified word before the next specific match or the end of the sentence.

For example HELLO * will match any two word or more sentence starting with HELLO

<?xml version="1.0" encoding="UTF-8"?>
<aiml version="2.0">
    <category>
        <pattern>HELLO</pattern>
        <template>Hi there!</template>
    <category>
</aiml>

Priority Matching

The priority special char $ is normally used when a zero or more, or one or more special character is included and you want to seperate out a specific word, but allow all other zero or one or more combinations to pass through

In the example below we watch to match all sentences whic start HELLO... but if any sentence starts HELLO FRIEND we give a slightly different answer to every other combination. In this example we use zero or more match.

<?xml version="1.0" encoding="UTF-8"?>
<aiml version="2.0">
    <category>
        <pattern>HELLO $FRIEND #</pattern>
        <template>Hi there, friend!</template>
    <category>

    <category>
        <pattern>HELLO *</pattern>
        <template>Hi there!</template>
    <category>
</aiml>

Set Matching

Sets are defined in a later section Sets Tutorial and more info can be found in Sets

<?xml version="1.0" encoding="UTF-8"?>
<aiml version="2.0">
    <category>
        <pattern>HELLO</pattern>
        <template>Hi there!</template>
    <category>
</aiml>

iSet Mactching

<?xml version="1.0" encoding="UTF-8"?>
<aiml version="2.0">
    <category>
        <pattern>HELLO</pattern>
        <template>Hi there!</template>
    <category>
</aiml>

Bot Matching

<?xml version="1.0" encoding="UTF-8"?>
<aiml version="2.0">
    <category>
        <pattern>HELLO</pattern>
        <template>Hi there!</template>
    <category>
</aiml>

Regex Matching

<?xml version="1.0" encoding="UTF-8"?>
<aiml version="2.0">
    <category>
        <pattern>HELLO</pattern>
        <template>Hi there!</template>
    <category>
</aiml>

Operator Precedence

In terms of precedence, the parser checks for each type of matching in a specific order defined by the following rules

	Precedence
		$	Priority
		#	0 or more
		_ 	1 or more
		word
		set
		iset		
		bot
		regex
                word
		^	0 or more
		*	1 or more

Star matching

Use of <star> tag

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