By Logic Programming I mean the a sub-paradigm of declarative programming languages. • There are various predicates and functions supplied to support I/O, graphics, etc. They also follow a declarative rather than an imperative approach. 2.1 Map colorings This section uses a famous mathematical problem -- that of coloring planar maps -- to motivate logical representations of facts and rules in Prolog. Prolog is a logic programming language. Mercury addresses the problems of large-scale program development, allowing modularity, separate … The classic methods of representing knowledge use either rules or logic. Nevertheless, logic programming does require special skills and attention to the order in which statements are executed. Conceptually, a rule is very simple: if A B C then D E Meaning, "if A, B and C are true, then D and E are also true". However, what does that mean? 15-819K: Logic Programming Lecture 1 Logic Programming Frank Pfenning August 29, 2006 In this first lecture we give a brief introduction to logic programming. It has important role in artificial intelligence. '); rule: a pattern-action declaration based on a fact (or other rules) expressed in … They don't do surveillance or interrogation. Often used in genetic and evolutionary programming, this approach generally tells a model what goal to accomplish, rather than how to accomplish it. The set of rules that specify the sequence of keywords, parameters, and punctuation in a program instruction is ... Prolog programming is all about facts and rules. PROLOG programs are composed of facts and rules. Control and logic are separated for this form of programming to work. Facts consist of a specific item or relation between two or more items. Of course, computers can only juggle the facts you provide. It was invented i… is_bigger(X, Y) :- bigger(X, Z), is_bigger(Z, Y). As in coinductive logic programming, interpretations are subsets of the complete Herbrand basis, including infinite terms. A logic is a language. The computer examines the query in the context of the rules and facts and determines the solution. A simple example Turing machine is specified by the facts: rule(q0, 1, q0, 1, right). Instead, the interpreter starts with the query and searches for applicable facts and rules that can be substituted for elements of the query until either the query is found to be true or all facts and rules have been tried that indicates there is no resolution. PREDICATE LOGIC • Can represent objects and quantification • Theorem proving is semi-decidable 37 38. z. 3 Prolog will attempt to return every solution – in the order that they occur in the program. You write down the things you know, write down the rules that hold true for these things, and then you ask questions. X, Y, and Z are variables, which in Prolog is indicated by using capital letters. Instead of a carefully structured control flow dictating when to execute and how to evaluate function calls or other instructions, the program’s logic rules … Prolog uses unification to match queries with rule heads and facts. These are often called if-then rules. true. What is a logic. Core heart of prolog lies at the logic being applied. Information provided to the computer in logic programs can be classified into facts and rules. Its highly optimized execution algorithm delivers efficiency far in excess of existing logic programming systems, and close to conventional programming systems. To understand how a problem can be solved in logic programming, we need to know about the building blocks − Facts and Rules − Similarly, we can assert the simple fact that Socrates is a person. That is why they are called the building blocks of Logic Programming. Logic Programming uses facts and rules for solving the problem. statements are called rules and are implemented like this: is_bigger(X, Y) :- bigger(X, Y). PROLOG interpreter has a deduction engine. In Prolog, facts are used to form the statements. Logic Programming - Prolog • Prolog is a declarative programming language based on logic. It has syntax and semantics. z. Syntax: the rules about how to form formulas; this is usually the easy part of a logic. We introduce a generalized logic programming paradigm where programs, consisting of facts and rules with the usual syntax, can be enriched by co-facts, which syntactically resemble facts but have a special meaning. • Prolog (programming in logic) is a logic-based programming language: programs correspond to sets of logical formulas and the Prolog interpreter uses logical methods to resolve queries. The … • A Prolog program is a list of facts. In Prolog programming, a(n) _____ represents one of the main subjects that a fact describes. Similarly, logic programming expresses facts and rules about the domain in which the developer is working. rule(q0, b, qf, 1, stay). The goal of this exercise is to enable the writing of functions like prolog_func(), where a collection of facts and rules can be written in a language reminiscent of Prolog and First-Order Logic. Table displays the knowledge for the zoo animals problem in two formats–using rules on the left as implemented within the Knowledge Representation NetLogo model, and using first order logic on … mortal (X) :- person (X). • Hence we go for PREDICATE LOGIC 36 37. Specific problems that we wish to solve in this domain are posed as questions or queries. •Prolog (PROgramming in LOGic) represents programs as logical Horn clauses and treats execution as answering queries with backward chaining. The key goals of the presentation are to show several important methods of knowledge representation in Prolog and the declarative programming methodology of Prolog. Representing Knowledge using rules in AI. They don't have intuition. 06-25433 – Logic Programming programming language particularly well suited to logic and artificial intelligence programming In these rules :- means something like \if" and the comma between the two terms bigger(X, Z) and is_bigger(Z, Y) stands for \and". • Prolog is a declarative language: you specify what problem you want to solve rather than how to solve it. For instance, the noun “sale” might be misrepresented by the noun “sail” in a sentence. Semantics: about the meaning carried by the formulas, mainly in terms of logical consequences. In another example in which logic errors exist, word processors might sometimes use an automated spell checker; these spell checkers are notorious for missing logic errors. The most popular logic programming language now is Prolog. Constraint logic programming combines both the above practices. z. Don't confuse this question with "What problems can you solve with if-then-else?" z. A goal needs to be specified for every program in logic programming. Example query and result: We also discuss administrative details of the course, although these are not included here, but can be found on the course web page.1 1.1 Computation vs. More than a language, it has inference rules. In prolog, logic is expressed as relations (called as Facts and Rules). PROLOG = PROgramming + LOGic; The following figure situates PROLOG in relation to other programming paradigms and languages [ESPP]: (adapted from [ESPP]) fact: an axiom is asserted to be true (e.g., `It is raining. Logic programming is about making computers deduce facts for you. Representing simple facts (Preposition) “SOCRATES IS A MAN” SOCRATESMAN -----1 “PLATO IS A MAN” PLATOMAN -----2 Fails to capture relationship between Socrates and man. person (socrates). • An important programming paradigm is to express a program as a set of rules • The rules are independent and often unordered • CFGs can be thought of as a rule based system • We’ll take a brief look at a particular sub-paradigm, Logic Programming • And at Prolog, the most successful of the logic programming languages This machine performs incrementation by one of a number in unary encoding: It loops over any number of "1" cells and appends an additional "1" at the end. • Instead of CNF, prolog uses an implicative Logic programming is a programming strategy that uses logic circuits to control how facts and rules are expressed, rather than only mathematical functions. Logical programming is a programming paradigm which has its foundations in mathematical logic. 4 CS 2740 Knowledge Representation M. Hauskrecht KB in Horn form • Horn form: a clause with at most one positive literal • Not all sentences in propositional logic can be converted into the Horn form • KB in Horn normal form: – Three types of propositional statements: • Rules • Facts • Integrity constraints (A∨¬B) ∧(¬A∨¬C ∨D) (B1 ∧B2 ∧KBk ⇒ A) Facts are rules that are always true. Backward chaining (or logic programming) is important for implementing complex searches. The first rule is simple and can be formulated as: For all X and Z, X is a predecessor of Z if X is a parent of Z. PROLOG SYNTAX: predecessor (X,Z):-parent (X,Z). In contrast to languages like Java or C, programs written in a logic programming languages such as Prolog are not composed of sequences of instructions but of a set of axioms, or rules which define relationships between objects. Prolog does not contain any statements that specifically "administer" the flow of the program. They can only do logical operations very fast, that's all we can expect from machines. Prolog Program Control. Unlike many other programming languages, Prolog is intended primarily as a declarative programming language. •Production system languages (OPS5, CLIPS) represent programs as rules that add and/or delete elements from working memory and treat execution as forward chaining inference. Let's look at the simple example in more detail. Like, “who killed John F. Kennedy”? In classical logic we might say "All people are mortal," or, rephrased for Prolog, "For all X, X is mortal if X is a person." This knowledge base of facts and rules describes the problem domain. Logic Programming. The programmer can focus attention on defining the rules and does not need to deal with the mechanics of backward chaining and backtracking. A declarative rather than how to form the statements using capital letters support I/O, graphics, etc objects quantification! 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