Facts, Beliefs, Truths, Goals, Statements

Off-late I've been busy reading about Semantics of Facts and Goals etc. There are many things in our day-to-day life that we come across. These are Statements, Facts, Goals, Beliefs, Truths, Obligations etc. Most of what we know or don't know fall in any (or more) of these categories. This made me thinking as what is this all about? What is the common thing among all these? What differentiates them? and many more questions pertaining to this topic.

Recently while researching on these topics I could draw these relations.

1. Statement is the common ancestor of Goal, Beliefs, Obligations, Truths, Facts etc.
2. Except Goal everything works is valid for a given time (has time component) and place.
3. Expression of goal needs two states for the same object. One is the initial state and one is the State of the object at any given time t when we claim the object has achieved the goal. The statement that an entity has achieved its goal is always in comparison to the state of entity at the time when the process to achieve the goal begun.
4. Beliefs change over period of time.
5. Facts are discovered not invented. They are present whether we know about them or not.
6. Facts belong to Closed-World semantics.
7. Beliefs belong to Open-World semantics and as discussed earlier they are constructed and can be destroyed as well.

I still have long way to go on this way. Any pointers from readers would be good.

PS: Its been almost 2 months since I had my last post on this blog. But I plan to come back in full swing soon and start posting regularly.

Until next time... !!!

Predicate and URIs

While going through different papers I realized that almost every research paper has different functions that do some common operations and work on two objects. Say isMotherOf(x,y) could be mother(x,y) and so on. Now the questions arises that if there are many such predicates exist in different knowledge base then how will someone know that they are related and they virtually do the same thing.

The Predicates are like function or relation-builder as they establish relationship between two objects. So we can very well say that the predicates are the base for our reasoning mechanism or determining what the two objects are all about. It also plays an important role in the context definition of the two objects.

This gives me a strong point to put forward the predicate being a URI so that two knowledgebase if they are using the same predicate or relation then they do mean the same thing. Using this principle a Reasoning Engine can be developed that can extract the meaning of the statements / facts etc in the system. If we design a system on this principle then the amount of ambiguity we need to deal with will be less.

The RDF facilitates the Predicates to be both URI and simple text, but in long run the simple text might look flexible or simple to work with but more people will use URIs for the predicate in RDF. Removing the ambiguity once and for all is a distant dream though. Even though we follow these principles, we will still have some duplicate predicates in the system. But somewhere along the line we need to develop a mapping that will assign aliases for both the predicates and based on popularity the less used one can be phased out in due course.

Until Next Time.....

Entities and Representing Facts

In my previous post I started a discussion about Inferencing and Facts. The biggest challenge we have is how to represent these facts in the computer system. Last week I was reading the paper "A Library of Generic Concepts for Composing Knowledge Bases" by Ken Barker, Bruce Porter and Peter Clark, Proceedings of K-CAP 01, October 22-23 2001.

In this paper the authors make a classification between Entities and Events. Entities are things that are and Events are things that happen. Events are states and actions. States are static situation brought about or changed by actions.

To elaborate further on this Entities are the state information or the facts. Actions apply on those entities. So if we revisit our earlier post the facts can be represented as attributes of an object. Like Sun rises in east can be represented as Rising Direction (Predicate) attribute of Sun (Subject) with a value East (an instance of type direction). Similarly we can also represent other facts mentioned in the earlier post.

Any second thought????

Until Next Time ....

Inferencing and Facts

In my previous post I started a discussion on Reasoning and Inferencing. Going by very definition of inferencing it is an act of attaining conclusion based on certain facts. But what is fact? The facts could be

• Universal Truths like Sun rises in east, it is winter in Australia.
• Statements about an object instance. Toyota Yaris, YRS Rego ABC 123. Here we are considering only about one car.
• A general statement about all objects of one type. Toyota cars are better than Honda in terms of easy maintenance (I am not going to start car manufacturer war here).
• Statement applicable to more than one type of object. If battery is down then none of the battery operated or petrol vehicle will start.
  

But the actual problem is not what the fact is. The problem begins when we want to store the fact for computer systems to understand and reason. We need to store them in our KnowledgeBase which is nothing else but a collection of facts about one or more entities. To store facts in KB we need to have few issues sorted out like:

1. How do we represent the facts in Computer System?
2. How do we link the facts to the entities they describe about?
3. How do we retrieve the facts and relate them to the entities?
4. How do we find all the facts that are known about an entity?

There are many such buzzing questions which needs to be answered before we go ahead with building a system that infers these facts. I would like to get an opinion from the readers as what their opinion is.

Until Next Time...!!!

Reasoning and Inferencing

Whenever I read about a journal or article on Artificial Intelligence, it sound like a science fiction to me. Okay okay I may not be up-to-date on my knowledge about what is happening in AI field. But more often than not what I find is most of the scenarios described in those fiction (?) are related to inference.

I read somewhere long back that Inference is the act of attaining a conclusion based on certain facts already present in the system. What are facts? In my opinion it is do to with the statements presented before us. But does the computers understand the statements as we do? I guess not. Then in relation to computer system the facts are the object, and their attributes. So we have few objects and their state information (as attributes) and we need to deduce a conclusion from that. How do we do that?

In order to combine these facts the system needs to have certain ability (A set of rules which will let us combine these facts together and infer something). This ability could not be anything else but Reasoning. By Reasoning we mean semantic relationship here. As we discussed in earlier posts that we need to have proper annotation in order to do Semantic Search and establish semantic relationship among entities in the system.

I guess I am getting more and more philosophical on this topic. I remember in our childhood we used to have a phrase. More Study More confusion, Less study less confusion, No Study NO Confusion :).

I would love to hear from readers about their opinion on relationship between Inference and Reasoning.

Until Next Time... :)