ANALOGY BETWEEN ‘CHEMISTRY’, AND ‘KNOWLEDGE REPRESENTATION IN ARTIFICIAL INTELLIGENCE’ -

 ANALOGY BETWEEN ‘CHEMISTRY’, AND ‘KNOWLEDGE REPRESENTATION IN ARTIFICIAL INTELLIGENCE’ - 

Consider this sentence - 

A gave a ball to B.

There are 6 words. Words are like atoms. They connect with each other to form a molecule called sentence.

There are 2 kinds of words/atoms - stable (independent) and unstable (dependent).

This difference is on the basis of their meanings. 

An unstable word depends upon attachment to other entities for the complete expression of its meaning. A stable word doesn't need that. So unstable atoms form bonds with other atoms in the molecule for stability.

For example, ‘ball’ is stable because you can define ‘ball’ independently of any situation or scenario. The meaning of a ball is ‘a spherical solid object used in games’…..something like that. But when one has to define ‘gave’ one has to take recourse to creating a background and invoking other entities; one says - when one transfers the possession of something to someone. Here, ‘when’,  ‘something’, ‘someone’ are things upon which the meaning of ‘gave’  DEPENDS upon for complete expression. These ‘some-X’ words don't come in while defining a ball or a pen or dance. But come in while defining ‘give’ or ‘preparation’.

When unstable words get into a sentence (molecule) they form bonds with other words. The stable ones don't form bonds with other ones FROM THEIR OWN SIDE. You could think of this as a co-ordinate bond - a directed bond. (Of course the stable words are INVOLVED in the bonds WITH the unstable words).

In the case of the above sentence, ‘A’, ‘ball’ and ‘B’ are the stable atoms. ‘Gave’, ‘a’ and ‘to’ are the unstable ones.

Lets see the bonds - 

1. A - gave

2. Gave - (a ball)

3. Gave - (to B)

4. A - ball

5. To - B

These are the bonds in the molecule - ‘A gave a ball to B’. The atoms in bold are the stable atoms.

Now, every direct (we will come to indirect bonds later) bond indicates a question-answer pair.

The corresponding Q-A pairs for the list of bonds above is - 

1. Who gave? A

2. Gave what? A ball

3. Gave to whom? To B

4. A what? As in, there was one (“a”) of what? Ball

5. To whom? B

Indirect bonds help in answering questions in general about the entities present in the sentence: How?

Bonds like ‘A - gave - a ball’ i.e. the bond between ‘A’ and ‘a ball’ are indirect bonds or ‘pathways’.

Now, any question will involve 2 atoms typically (X and Y) and some blah blah blah in it. Mostly the pathway between the atoms X and Y (i.e. the indirect bond) will be the answer to the question.

For example, ‘what did A do to the ball’? The pathway or the indirect bond says - A GAVE a ball.

Whereas if someone asks - Did the ball give? Here there is no pathway / indirect bond between ‘ball’ and give. So the answer doesnt exist, which  is indeed true. There is nothing like “the ball giving” mentioned here.

Inspired by the above 2 points - direct and indirect bonds - one can say that all the “sub-semantics” of the sentence (i.e. all the sub-information contained in the sentence) can be represented by the BONDS.

We can define Isomers also. Molecules with the same words but different bonds. That is, ‘A ball was given by A to B’ is an isomer of ‘A gave a ball to B’.

All the coordinate bonds have an electron-pair. This “unsaid content” of every co-ordinate bond (the electron-pair) is the commonsense about that linkage that can be placed above the bond. For example, for the bond : ‘A - gave’, what can be written above that bond hyphen is ‘with his hands’ i.e. the hidden unsaid invisible part of the bond.

If the sentence was - A gave a house to B, then on the bond ‘A -gave’ can be placed the commonsense ‘by transferring the papers’ & on the bond ‘gave - (a house)’ can be placed the commonsense ‘all the contents of the house’’. 

What happens when molecules come close to each other? They react with each other - their atoms react. Similarly, when 2 sentences follow each other, their atoms bear relationships with each other (ones from each sentence with the others). Such analysis can be done. (Terms like “reactivity”, “breakage of bonds”, “formation of new bonds” can be invoked…. !!)

For example, the pronoun applicability of a pronoun in the second sentence to the atoms in the first sentence can be seen in this light.

This work can be extended by drawing further analogies between the 2 concept-domains.

Finally, a picture of the molecule -