Neural Network Design blog

‘A because B’ and ‘Why C’ are 2 tricky statement types for a chatbot to handle correctly. Not only does the data need to be stored and retrieved correctly, but often, some words need to be replaced, like ‘I’ vs ‘you’. Here are some possible techniques you can use with the chatbot designer to handle such input.

Because

Let me first give an example of a ‘because’ statement that a user might say:

I have a dog because I like animals.

This statement is a bit of an oversimplification, perhaps just right for an example.   It doesn’t only specify why I have a dog, but also that I have a dog and that I like animals. All this data should be stored and retrievable so that the system can answer questions like:

Why do I have a dog?

Do I have a dog?

Do I like animals?

So, before we can store the data, we need to find an input pattern that’s able to handle ‘I have a dog because I like animals’. To start with, we could do something like:

I have a $value because $reason [.]

This can work for many possible input values, except that the ‘I’ vs ‘you’ change is difficult to do since there is no knowledge of the context (‘you’ can change into ‘I’, ‘me’,… depending on the context), so this is the least usable pattern, but there are other possibilities.  For example, lets take:

I have a $value because I like $object [.]

or better:

I have a ^value:noun because I like ^object:noun [.]

With this input pattern, we are able to extract all the valid data so that it can be stored in memory and we also have static text for ‘I’, which can easily be transferred manually. A small improvement might be to replace ‘$value’ with ‘^value:noun’ so that only a proper noun can be captured instead of things like ‘I have a pretty big keyboard on my lap sitting there because I like typing’. The same goes for ‘$object’. As in the previous example, ‘typing’ could probably better be transformed to ‘type’ before you store it, so in the pattern you could replace ‘$object’ with ‘^object:verb’ or ‘^object:noun’,… Anyway, lets take a look at how the do-patterns would look like for storing this info:

#user += $value

#user.like.($object) = yes

#user.($value):why = “because you like $object”

In the first line, we create a ‘has’ data item for ‘$value’. The second line adds the ‘object’ to the ‘like’ list, with the value ‘yes’ so that it’s clear the user likes it. And the third line stores the reason why the user has a ‘value’. ‘:why’ is a function that provides access to the ‘reason’ data-tree. What you store in ‘:why’ is completely up to you. In this example, we store a text, between brackets, cause I wanted to preserve the spacing, but you could also treat it as a sub asset (or anything else, like a link to another rule), allowing you to write paths like #user.($value):why.object.

Why

Once you have stored  the information, you can retrieve it again if the user asks a why question. Here’s a possible input pattern that you could use for capturing this question:

Why do I have a $value [?]

or better:

Why do I have a ^value:noun [?]

And the output pattern could look something like:

You have a $value #user.($value):why

or better:

Bot says when:  #user.($value):why

You have a $value #user.($value):why

else:

I don’t know why you have a $value

That was easy enough. The first line is the most basic approach, the only problem with it: if the bot doesn’t know, it returns ‘You have a’. Which is no good. Better to put it in a conditional and check if there is a ‘why’ value, if there is non, let the bot say it doesn’t know. To check if there is a ‘why’ value, simply put the path in the ‘when’ close. This will check if the result of the path has a value. To check if it doesn’t have a value, use the not (!) operator in front of the pattern, like so:

Bot says when: !#user.($value):why

I don’t know why you have a $value

else:

You have a $value #user.($value):why

Improvements

Right now, we have a working system to handle because/why type of things, but it’s not very flexible, I mean, there are tons of reasons why you can have something, and not just because you like something else. Also, there are more people then just ‘I’, so lets improve the input patterns a bit and make things more flexible.

Using the Thesaurus

Lets start with ‘I’. As you had probably already guessed, the thesaurus variables are ideally suited for this. So, here’s an improved input pattern:

^s:pronoun.subject (have|has) a ^value:noun because ^w:pronoun.subject like ^object:noun [.]

Ok, that’s already a bit more complicated. The ^s variable can capture any child of the pronoun ‘subject’.  If you check in the thesaurus, under the pronoun POS, there are a bunch of greyed-out items, one of which is ‘subject’. These are ‘placeholders’, that is: these thesaurus items don’t actually contain a word, only a label. So our ^s variable can’t actually catch the word ‘subject’, but only it’s children: I, you, he, she, they, we, it.

The do-patterns also become a bit more complicated, since we will now have to calculate the inverse of the pronoun and we also have to extract the asset out of it. Luckily, there are some helper functions for this:

#($s:ResolvePerson) += $value

#($w:ResolvePerson).like.($object) = yes

#($s:ResolvePerson).($value):why = “because &w:InvertPerson ^verb.like:conjugate($w:ResolvePerson) $object”

:ResolvePerson is able to extract the asset (or concrete representation) out of a word.  At the time of writing: I and you  are supported. Names, ‘He’, ‘she’, ‘it’,… need some further testing.
:InvertPerson uses thesaurus links to jump from one person to it’s inverse, if there is one. So ‘you’ becomes ‘I if ‘you’ was used as a subject.
:Conjugate will try to find the correct conjugation of a verb, based on the argument that is supplied. This has to be an asset, usually the asset representation of the sentence-subject. So if you want to conjugate for ‘I’, you pass in ‘#bot’. ‘You’ becomes ‘#user’, and so on.

Split the patterns

The second improvement that we can make to the pattern is a bit more radical and relies on a special feature of the pattern matcher. You see, the pattern matching process is not restricted to finding just 1 pattern in the input. It will try to find the longest possible sequence of patterns that it can. That is, if the same words can be caught with a single pattern, this pattern will get precedence over a sequence of patterns. But if the pattern matcher can do a longer match by using 2 patterns instead of 1, that will become the result. This allows us to split up the first part of the sentence: ‘I have a $value’ from ‘I like $object’. opening up a whole new range of possibilities, and more importantly: saving use lots of duplicate work. The do-patterns become a little different though. First the input-patterns:

Topic: HAVE

^s:pronoun.subject (have|has) a ^value:noun

because ^s:pronoun.subject (have|has) a ^value:noun

 

Topic: LIKE

^w:pronoun.subject (like|likes) ^object:noun [.]

because ^w:pronoun.subject (like|likes) ^object:noun [.]

As you can see, not much has changed except that they are now 2 sets of patterns and each set has a version with and without ‘because’ in the front. We could also have written them as:

Topic: HAVE

[because] ^s:pronoun.subject (have|has) a ^value:noun

Topic: LIKE

[because] ^w:pronoun.subject (like|likes) ^object:noun [.]

But we aren’t. Instead, we keep each input-pattern in it’s own rule so that each can have it’s own set of do-patterns. This way, the ‘because’ version can be treated differently. Basically, what it comes down to is this: when there is no ‘because’, we simply store an extra memory field called ‘subj’ which allows us to recall the left part of the asset operation (excluding the attribute). When we have a because, we check if the ‘subj’ field is set and if so, we store the ‘:why’ in this field. Here are the do patterns:

Topic: HAVE

#bot.who = $s:ResolvePerson

#bot.Inverted = “#bot.Inverted because $s:InvertPerson ^verb.have:conjugate(#bot.who) a $value”

#bot.attribute = $value

#bot.who += $value

#bot.value = #bot.who.($value)

#bot.Subj = #bot.Who

#bot.Subj.(#bot.attribute):why = “because $s:InvertPerson ^verb.have:conjugate(#bot.who) a $value”

Topic: LIKE

#bot.who = $s:ResolvePerson

#bot.Inverted = “#bot.Inverted because $s:InvertPerson ^verb.like:conjugate(#bot.who) $value”

#bot.value = yes

#bot.attribute = $value

#bot.who.like.($value) = yes

#bot.Subj = #bot.who.like

#bot.Subj.(#bot.attribute):why = “because $s:InvertPerson ^verb.like:conjugate(#bot.who) $value”

The full code example can be found in {documents}\NND\Demos\Why_Because2.dpl. As you can see, it’s a bit more code then where we originally started. Though if you look a little closer, a lot of it is boiler-plate stuff: store who, attribute, value, subj, inverted.
Key advantage here: with only a few patterns we can have any type of combination: have because like, like because have,  have because have, like because like, because have, because like, have, like, have because like because have,….

The basic set-up is always the same, we dissect the sentence into it’s parts so that they can be reused in other parts. here’s what we need:

• calculate ‘who’ (the asset form of the subject part in the sentence = I, you, he,…) so we can reuse it and don’t have to recalculate it each time.
• store the the inverted sentence, for output generation (can always be useful)
• the attribute and value (‘color’ is the attribute of ‘yellow’). In this example, strictly speaking not really required, but other parts of the concept rely on this data, so best to get used to it.
• subj: sometimes, the ‘who’ isn’t enough to find out where some data needs to be stored. ‘like’ (and most other verbs) is a good example of this. So if we want to get to the correct data path later on, we need to store this new path, hence the existence of ‘subj’.
• If ‘when’, ‘where’, ‘how’,… is also present in the sentence, these are all data parts that can be stored like attribute, value or more complex sub structures.

There are a few extra do-patterns required to get this working correctly. The ‘who, inverted, value, attribute, subj’,… fields of the #bot are all temporarily, that is: they are supposed to be used as mid-term memory, for as long as the current input is being processed, so that the information can be passed along from one pattern to another. This means that we need to remove the data after the input has been processed so that it wont interfere with any of the next input. This can be done from the Chatbot’s properties view (select the menu item view/chatbot properties, next go to the ‘Do after output’ tab.). here’s how it would look like for this example (can be simplified, which we will do in the next example):

#bot –= Inverted

#bot –= Who

#bot –= Subj

#bot –= attribute

#bot -= value

Also, in this example, I only used thesaurus variables. You can achieve similar results with regular variables, but there has to be a small change in the pattern definition for it to work properly. Everything has to do with the fact that a regular variable can only determine it’s end by what is defined after the variable, and if the pattern definition ends with a regular variable, it will collect the remainder of the input and never jump to another pattern. So we need to put something behind the variable if the ‘because xxx’ needs to be handled correctly. This can be done by moving the ‘because’ from front to back like so:

Topic: HAVE

I have a $value [.]

I have a $value because

Topic: LIKE

I like $value [.]

I like $value because

The biggest disadvantage: you need extra patterns to handle a ‘because xxx’ (not shown or included in the demo), but on the plus side, the do-patterns become a little simpler using this type of pattern definition style. For a complete example, see: {Documents}\NND\Why_Because.dpl.

Sub topics

There’s one more trick we can use to make the patterns more flexible and which will also resolve a final problem caused by using multiple rules as we did in the previous step. You see, finding a list of unrelated rules is primarily done to recognize multiple sentences in the input and not for splitting up a single sentence. That’s because all the outputs from those rules are always automatically combined. So you can’t change the order or content. This can make output management a little tricky.

The solution comes in the form of sub-topics or sub-rules. With this technique, it’s possible to reference a topic or rule by it’s name from within a pattern in the same or other topic. This allows us to split the ‘because’ out into a third topic and then group them all back together into a single rule, which will be the final, single result. So, on the input side, it becomes more flexible, and thanks to a special variable ‘$output’ and a switch in the chatbot properties, we can also take control of the output side. more on that later, lets first start with the input patterns, how do you declare sub-topics?

Topic: HAVE

^s:pronoun.subject (have|has) a ^value:noun

Topic: LIKE

^s:pronoun.subject (like|likes) ^value:noun [.]

Topic: BECAUSE

because

Topic: BECAUSEHANDLER

~have

~like

~becauseHandler ~because ~becauseHandler

The first 2 input patterns should be familiar by now, nothing has changed since before, only the ‘because’ version has been eliminated. The first new topic is also nothing special, just a single word ‘because’.  The magic happens in the last topic, which groups all the other topics together.

~ is used to indicate a Topic reference. It’s always followed by the name of a topic and possibly a dot followed by the name of a rule. It’s meaning is simple: include all the patterns in the rule(s) of the specified topic at the location of the reference. Here’s an example for sub rules:

~have.statement because ~like.statement //presumes that topics ‘have’ and ‘like’ have a rule labeled ‘statement’

Now, if you look at the last topic: ‘BECAUSEHANDLER’ you’ll notice that it only contains references to other topics, it’s a root topic. In this example, it’s purpose is to provide a place to declare the output for every topic, so we can combine things correctly + it also stores the ‘why’ relationship. Also, if you look at the last pattern, it references it’s own topic, 2 times. This is recursion and allows us to recognize a sequence of ‘becauses’ like: I have x because I like y because I have z,….

You might be wondering why it’s the BECAUSEHANDLER that stores the ‘:why’ link and not the ‘BECAUSE’ itself. That is because at the time of the ‘Because’ pattern, the reason is not yet known (this is defined in the next pattern, which hasn’t been processed yet), so it can’t link anything up yet. To overcome this, we make certain that there is an extra rule that gets executed after every other part of the sentence: the BECAUSEHANDLER.  In other words, the ‘becauseHandler’ is a way to perform some code after all the patterns have been processed.

By the way: topic names can be edited in the ‘project view’ (select the topic, press F2 or right mouse click/rename). A topic name should be unique within the project if you want to use it as a sub-topic, otherwise it’s not that important, but the UI will always warn about duplicate names and those topics will have a red icon instead of blue. The name of a rule is always visible in the ‘description view’s title when the rule is selected.  It can be changed in the topic editor: select the entire rule (don’t click on a pattern, but on the background of the rule). With F2, you get a dialog to change the name.

Let’s continue with the do patterns.  For ‘have’, ‘why’ and ‘like’, they remain very similar: the patterns are used to store the inverted sentence, who (asset), the attribute, the value and the ‘subject’. In this example though, instead of directly storing it under the ‘bot’, it is stored underneath ‘mem’ so that we can move the entire result set with 1 statement later on. So here’s a small example of the ‘have’ do-patterns:

#bot.mem.attribute = $value

#bot.mem.who = $s:ResolvePerson

…

And so on. The really interesting stuff happens in the ‘BECAUSE’ and ‘BECAUSEHANDLER’ topics. Note that this time, we have some do-stuff in the ‘calculate’ area and others in the ‘do’ section. The major difference here: ‘Calculate’ is done, just before any of the conditions are evaluated, so this allows us to do pre-calculations that can be used in those conditions.

Topic BECAUSE:

#bot.because = #bot.mem

#bot -= mem

Topic BECAUSEHANDLER:

Rule ~becauseHandler ~because ~becauseHandler

Calculate:

$result = “because #bot.mem.Inverted”

$path = #bot.because.Subj.(#bot.because.attribute)

Output when: #($path):why == $result

Yes, I now #bot.because.inverted because #bot.mem.inverted\.

else

I see, #bot.because.inverted because #bot.mem.inverted\.

       Do

#($path):why = $result

Rule ~have

$output

First off, BECAUSE: this moves the ‘mem’ field to ‘because’ and ‘mem’ is cleaned/deleted. Basically, we store the data of the previous sentence and prepare to collect the data for the next sentence. The ‘because’ field will later on be used to link to the newly collected ‘mem’ field. Note that this rule doesn’t generate any output.

Secondly comes the ‘BECAUSEHANDLER’. This builds up the result that needs to be stored in ‘:why’ and calculates the location where this info needs to be stored (in $path). Before actually committing the data to memory though, a check is done to see if it was already known. If so, a different response is given compared to when it is not yet known. In the latter case, the info is also stored.

For the other rules (~have and ~like), we simply declare the $output variable in the output section, indicating that we want to reproduce the output of previous topic.  Note that the use of this $output variable can be controlled in the chatbot’s properties view. When turned off, it will function as a regular variable, and the output of all the patterns will simply be combined. This allows you to select between a simple styled bot or something more advanced.

Finally, as already mentioned, we still need to do some clean-up after the input. Since we have grouped all the mid-term memory in 2 fields: ‘mem’ and ‘because’, cleanup becomes a little simpler (Note: sometimes the ‘because’ part doesn’t exist, but that’s ok, nothing will be removed in this case):

#bot –= Mem

#bot -= because

I guess that’s about it for now.

Well, we went from simple, straight forward, fire-cracker-leveled patterns to something that’s more akin to ‘rocket science’. The combination of memory, thesaurus and sub-topics might just turn out to be a very explosive mix. I for one, am very interested to see where all this will eventually lead too… Stay tuned.