Y = Frank in Java

Make QR Code in Java Y = Frank

In other words, Frank is the grandfather of Sally (Frank is the father of Jesse, and Jesse is the father of Sally) Just from this simple example, you can see how different a Prolog program works compared to a program written in BASIC or C Instead of telling the computer how to solve a problem, declarative programming languages let you state the facts and the rules for manipulating those facts so the computer can figure out how to solve the problem

A Prolog program can actually create additional facts (and delete old facts) while it s running, so it can appear to think That s why Prolog is commonly used in the field of artificial intelligence The whole idea behind artificial intelligence is to make computers smarter and literally think for themselves (That s because computer scientists have pretty much given up hope that people will ever get smarter or begin to think for themselves) Just as knowing two or more human languages can help you better understand how people communicate, so can knowing two or more different programming languages help you better understand how programming can work The key is to figure out two different programming languages, like C++ and Prolog Knowing two similar programming languages, like C++ and C#, doesn t show you much of a difference One of the most popular programming languages favored by the artificial intelligence community is LISP (which stands for LISt Processing) The basic idea behind LISP is that everything is a list that can be manipulated by the computer For example, a typical LISP command might look like this:

(print Hello world )

This LISP command is a list that displays the following on-screen:

The enclosing parentheses define the start and end of a list A different way to print Hello world on-screen would be to use this LISP command:

(list Hello world )

The preceding command would print the following:

( Hello world )

In this case, the list command tells the computer to treat Hello world as a list, so it encloses it in parentheses Now consider what happens if you insert a command (list) inside another command (list):

(list (print Hello world ))

This is how the preceding LISP command works:

world ) list This displays the following on-screen:

looks like this:

(list Hello world )

This command now displays the following on-screen:

( Hello world )

(list (print Hello world ))

prints the following:

Hello world ( Hello world )

In the previous example, LISP treats the (print Hello world ) list first as a command (to print Hello world on-screen) and then as data to feed into the list command to display the list ( Hello world ) on-screen With traditional programming languages, like C or BASIC, commands and data are separate where data may change but commands never change With LISP, a list can be both a command and data That makes it possible for a program to change its lists (treated either as data or as a command), essentially allowing a program to modify itself while running, which can mimic the learning and thinking process of a human being As you can see, both LISP and Prolog offer radically different ways to program a computer compared to C or BASIC Just as languages, like C and BASIC, free you from the tedium of manipulating registers and memory addresses to program a computer, so do LISP and Prolog free you from the tedium of writing explicit step-by-step instructions to program a computer Although the idea that a LISP program can modify its own commands might seem like science fiction, LISP is actually the second oldest programming language still in use today (FORTRAN is the oldest programming language still in popular use) LISP was invented in 1958, and although it s been used primarily as a research tool, people have created commercial programs using LISP