Chapter 6: Agents that Reason Logically

1.) what is a knowledge-based agent? A knowledge-based agent includes a knowledge base and an inference system. A knowledge base is a set of representations of facts of the world. Each individual representation is called a sentence. The sentences are expressed in a knowledge representation language. The agent operates as follows:
• It TELLs the knowledge base what it perceives.
• It ASKs the knowledge base what action it should perform.
• It performs the chosen action.

2.) What are syntax and semantics? Syntax, which defines all possible sequences of symbols that constitute sentences of the language. Examples: Sentences in a book, bit patterns in computer memory. Semantics, which determines the facts in the world to which the sentences refer.
• Each sentence makes a claim about the world.
• An agent is said to believe a sentence about the world.

3.) What is an inference? Inference is the process of drawing a conclusion by applying clues (of logic, statistics etc.) to observations or hypotheses; or by interpolating the next logical step in an intuited pattern. The conclusion drawn is also called an inference.

4.) What is logic? Logic is for constructing proofs, which give us reliable confirmation of the truth of the proven proposition. It's the formal systematic study of the principles of valid inference and correct reasoning. Logic is used in most intellectual activities, but is studied primarily in the disciplines of philosophy, mathematics, semantics, and computer science.

5.) What is a propositional logic? A propositional calculus or logic (also a sentential calculus) is a formal system in which formulae representing propositions can be formed by combining atomic propositions using logical connectives, and in which a system of formal proof rules allows certain formulæ to be established as "theorems". Propositional logic is a good vehicle to introduce basic properties of logic. It does not provide means to determine the validity (truth or false) of atomic statements. Instead, it allows you to evaluate the validity of compound statements given the validity of its atomic components.


References:
www.cs.umbc.edu/courses/671/.../c10_kb_agents.ppt - Estados Unidos
http://turing.une.edu.au/~comp292/Lectures/HEADER_KM_2004_LEC_NOTES/node45.html
http://www.google.com.ph/search?hl=tl&biw=1024&bih=498&defl=en&q=define:inference&sa=X&ei=27RmTciVCIvtrQeRtODaCg&ved=0CBUQkAE
http://www.rbjones.com/rbjpub/logic/log001.htm
http://en.wikipedia.org/wiki/Logic
http://en.wikipedia.org/wiki/Logic#Propositional_logic_.28sentential_logic.29
http://en.wikibooks.org/wiki/Logic_for_Computer_Science/Propositional_Logic

1. what is a knowledge-based agent?

For me, I think knowledge-based agent is an intelligent agent which is program to act as an assistance to human task. In other words, it is like having an own initiative when dealing of certain things.

http://turing.une.edu.au/~comp292/Lectures/HEADER_KM_2004_LEC_NOTES/node45.html

2. What are syntax and semantics?

With regards to syntax and semantics, I always encounter this kind of a question asking what these both mean. When we say syntax, this term refers to the grammatical structure itself while semantic refers to the meaning of the structure. For example, " The bird is crawling". The sentence is grammatically correct but the meaning makes no sense. In other words, syntax and semantics coincide with each other.

http://www.jguru.com/faq/view.jsp?EID=81

3. What is an inference?

The term inference is simply an act of drawing a conclusion by deductive reasoning from given facts . Such example is,

All men are mortal.
Socrates is a man.
Therefore, Socrates is mortal.

Inference is something to do with validity but it does not refer to the truth of premises, but rather to the form of the interference.

http://en.wikipedia.org/wiki/Inferenc

4. What is logic?

I always find logic as mind freaking and critical because it requires correct reasoning. It solely depend on how a person treat the problem and how he/she understands it. In other words, it is used in most intellectual activities but is studied primarily in the disciplines of philosophy, mathematics, semantics and computer science.

http://en.wikipedia.org/wiki/Logic

5. What is a propositional logic?

Propositional logic also known as sentential and statement logic which studies logical operators and connectives that are used to produce complex statement. In addition, it is assumed that every statement is either true or false and not both. There is also a consideration of connectives used to produce statements whose truth-values of the parts, but additional things such as their necessity, possibility or relatedness to one another.

http://www.iep.utm.edu/prop-log/

The concept of this agent is a knowledge base or simply KB. Formally, KB is a set of representation of of facts about the word. Usually, these agents have several representations depending on the environment or the level of intelligence that they used it.
To make it detailed about that, this agent is composed of a knowledge base and an interference mechanism which operates by storing sentences about the world in its knowledge base.

The syntax of a language describes the possible configurations that can constitute sentences. In computer system/or a programming language, it is a set of commands that represent this system and it is readable to the machine though the computer systems (one of those is the compiler).

This determines the facts in the world in which the sentences refer. With these, the group of syntax will give meaning or sense to the commands to be placed in the computer system.

In Logic, the main concentration is sound reasoning. And that term is called logical inference or deduction. It is a process that implements the entailment relation between sentences. It also the process of deriving new sentences into old ones.

Based on the previous definition, thisis the formal systematic study of the principles of valid interference and correct reasoning[1]. It also useful for the commitments about what the world is made of and what gives the knowledge base writer more freedom.

This commits only the to the existence of the facts that may or may not be the case in the world being represented. It has a simple syntax and semantics that suffices to illustrate the process of interference.
This is known as a very simple logic.