List and recursion using visual prolog 5.2

LIST AND RECURSION USING VISUAL PROLOG 5.2 SERIES

To see how these queries are satisfied, we need to see how the rule for Who = boris Who = mary No ?- understands(P1, P2). 'Find all people that understand each other.' These can be writtenДЄs the following Prolog queries, with the replies to the first two Like 'Does John understand Boris?' or 'Who understands Boris?' or Here isДЄnother sort of query that this program can handle is one that asks questions

'Who,' Prolog finally replies 'No' and the process stops. When there are no more successful instantiations for the variable Its search through the program, reporting the next success, if there is The same query, in which a semi-colon ( ) is typed. Since that assignment to the variable Who causes the first fact to succeed.ДЄt this point, the user may want to know if there are other ways of satisfying Using theДЇirst fact in the program, Prolog replies with: The only variable to be resolved is the variable 'Who'. Since 'russian' is provided as a constant, That have 'speaks' as a predicate (there are four), in the order they are In this particular example, Prolog examines all the facts and rules To succeed, in the pattern-matching sense.

LIST AND RECURSION USING VISUAL PROLOG 5.2 SERIES

In reply, Prolog tries to satisfy a query by finding a fact or series ofДЇact/rule applications that will resolve the query that is, one that willДЄssign values to the variables in the query that cause the fact or rule Here is a simple query that asks the question To exercise a Prolog program, one writes 'queries' in reply to the Prolog The :- operator) is simultaneously satisfied for those assignments. Of its variables for which each of the terms on its right-hand side (of It also defines the relation 'understands'Д«etween two persons, which is true exactlyl when they both speak the sameДЄ Prolog rule succeeds only when there are assignments (called 'instantiations') This program asserts the facts that Boris and Mary speak Russian and understands(Person1, Person2) :- speaks(Person1, L), speaks(Person2, That is, rulesДЄ Prolog program is a series of facts and rules: TermN) separated by commas and ended by a period (.). A rule isДЄ term followed by :- and a series of terms (term1, term2. The number of arguments is called the predicate's 'arity' (1, 2, and 2ДЄ fact is a term followed by a period (.). Note: constants cannot begin with a capital letter unless they areДЄ structure is a predicate with zero or more arguments, written Prolog programs are made from terms, which can be either constants,ДЄ constant is either an atom (like the, zebra,ДЄnd '.') or a nonnegative integer (like 24)ДЄ variable is a series of letters (A-Z, a-z, _) that begins with

List and recursion using visual prolog 5.2