Academics Information Technology IT

Logic Programming: What are its Techniques

Logic Programming

The topic in context here is the introduction to Logic Programming. It is a vast concept with diverse sets of information regarding the programming language. It would not be possible to delve deep into every aspect of the topic and discuss extensively every topic that pertains to the issue.

Hence a quick overview of Logic Programming would be made and almost every aspect related to it would be introduced allowing framework for further studies and a current basic understanding.

The first question that arises is what is logic Programming? Before that is answered the discussion of anything related to it would not hold any real value. Logic Programming is a kind of programming paradigm. A number of computer programs are formulated in terms of logic programming.

It is to be noted that any program which is written in terms of logic programming consists of a group of sentences in a logical format. These sentences express a set of facts or rules about some domain of a problem. Besides this, there are a number of logic programming families that exist. The mentionable ones are Prolog, Answer Set Programming abbreviated as ASP or Datalog.

However, what is common in all these languages is that the rules in the program are expressed in the form of clauses which is explained in point 1 and are inferred as logical explanations which are explained in point 2.

  1. H: B1, B2, B3, B4,…….Bn
  2. H if B1, B2, B3….and Bn

In logic programming, H is taken to be the head of the rule. In addition to this, B is known as the body of the rule. If we look back, the concept of facts has also been raised. Facts, in reality, are the rules which have no bodies. It is demonstrated with just H.

Logic programming does not always necessary pertain to the simple cases of programming. A simple case can be considered where the head and body of the rule expressed as H and B1, B2, et cetera are the atomic formulae. In this case, the clauses are named as Horn clauses or Definite clauses. Besides this, there can be a few other extensions beyond this simple case too.

One of the most important of these extensions is that when the clauses are in absolute negation to the atomic formula as discussed above. Consequently, the languages in logic programming which work in accordance with these extensions have the capability of representing knowledge in the form of non-monotonic logic.

A brief detail should also be made about the other logic programming languages in addition to Prolog which includes ASP and Datalog. These programs include a kind of reading which is just declarative. In terms of its execution, the process involved is model generator and proof procedure. However, these processes of execution are not generally under the voluntary control of the programmer.

But if we take into account the Paralog language, it is seen that it has a system of interpretation which is procedural. It is primarily done as a process of goal reduction. For example, in order to solve the head of the rule which is H, the body of the rule too, including B1, B2 to Bn, everything has to be solved. Now our experts from Assignment Help Canada will tell you about the history of Logic Programming.

History of Logic Programming

The first appearance of logic programming goes back to the 1930s, developed by Alonzo Church, as a feature of the lambda calculus. This was the first use of mathematical logic in computers sciences. Apart from the developer, Cordell Green was the first one to propose the use of the clausal form of Logic as the representation of computer programs. In 1960-1970, a debate arises about the declarative versus the procedural representation of knowledge about artificial intelligence.

This is where the current form of logic programming can be traced. The advocates of each procedure were working in different places. In Stanford, alongside Cordell Green, there was John McCarthy, Bertram Raphael and in Edinburgh, Alan Robinson, Pat Hayes and Robert Kowalski. While the advocates of the procedural representations were in MIT(Massachusetts Institution of Technology), with Marvin Minsky and Seymour Papert as the head of the study.


What is Logic Programming
What is Logic Programming

Techniques

In widespread discussions about logic programming, a number of aspects have been discussed, including its pros and cons. Consequently, throughout all of these discussions, it has been established that the adoption of a compact and precise as well as formal semantics framework for a programming language in logic programming is extremely helpful in terms of understanding that language.

This idea specifically holds good for those languages in logic programming where the underlying logic puts forward a semantic framework which is well defined but even then it is insufficient. In addition to the semantic models supported by models and theories, proof-theoretic deduction plays a paramount role in the inference of logic programs. Therefore, apart from the general implementation, if the specific context of logic programming, for example with specific languages, the provision of the strategy of deduction proves to be more useful than the others.

As a technical approach to the concept of logic programming, the semantic framework for two specific kinds of logic programming languages has been taken up at the earnest. After determining the semantic framework, the applications of these semantic are also discussed.

The two languages discussed here are PROLOG and TEMPLOG. The semantics for PROLOG programs are issued which are most importantly used for forming the basis of the proof-method for the properties of termination of the same language. When TEMPLOG is considered, it is to be noted that it is a logic programming language which is temporal in nature.

The aim is to develop a semantics framework and then that technique is used to deliver completeness in result for a rather fragmented or divided section of the temporal logic in the logic programming.

 In the techniques used in the PROLOG language in logic programming, besides the general frameworks, some specific frameworks are also put to use. For PROLOG, a program is most importantly viewed as a function which is supposed to map a goal to a finite as well as infinite sequence of the substitution process in terms of the answer.

After this is done, the inference of the program in context is then given by a solution which is the least in the system of equations putting forward functionality. In addition to this, these equations are used in a theory in which the varied properties of the program, specifically the properties related to termination and non-termination are proved. The method discussed here also pertains to other PROLOG logic programs which have added logical features.

Now, the programming language of TEMPLOG is considered. For this language, the technical framework is a bit different. For this language, two equivalent formulations are provided. They work in terms of semantics which are declarative in nature. The two equivalent frameworks are first put forward on the basis of a temporal Herbrand model which is minimal. In addition to this, the second basis is the least fixpoint.

Therefore, these technicalities can be used to prove that the language of TEMPLOG in logic programming is a part of the temporal logic. It also takes into consideration that the temporal logic is a part of a system which is considered to be full-proof. This framework also helps to get an insight into the expressive parameter of logic programming on the basis of this language. For this framework to function effectively, it is important that the TEMPLOG in terms of the provided propositions has the expressive parameter of not only finite automata but also a regular language. Our Assignment Experts will tell you about the concepts.

Concepts

One important concept associated with logic programming is the concept of logic and control. Logic Programming is basically a means of deduction language which is controlled. One of the most important concepts is the demarcation of the concept of logic with the concept of control in a program.

That is one of the most important things that help in the effective functioning of logic programming. In the languages that confide in pure logic, the component of logic solely determines the solution which is produced. The component of control, in that case, is put to alternative lines of execution in the logic program.

This can be defined by the simple formula that an algorithm is the summation of logic and control. Here, the logic is described as the logic program and the control is defined as a strategy which helps in proving a theorem.

In a case of propositions which is simple, the logical program, as well as the atomic goal, contains no variables whatsoever, and there is no chance of choosing backward variables, the context of search space comes into view for solving the goal in context. It is considered that the top level of the goal is the root of the tree.

In addition to that, there are also a number of child nodes in the tree naturally which personify the subordinate goals in the program. These child nodes or the subordinate goals are put under the same roof by an “and”. The alternative nodes that are present are considered as the alternative sets of goals and they are put under the roof of “or”. IN reality, any kind of search strategy can be used to conduct a search in this space. PROLOG as a language in logic programming uses a strategy which is characterized by backtracking.

In addition to that, it also uses the Last in First Out method. The method used by PROLOG is sequential in nature. In this method, one alternative goal in addition to one subordinating goal is in context. Other strategies of search can also be discussed here. These are intelligence backtracking, parallel search, and many others.

These are adopted to find an optimal solution. Another case can also be considered where the subordinate goals share the variable which is present in the program. In this case, alternative strategies can be put to use. These are the kinds of strategies which are to be found in the concurrent logic programming.

Another concept associated with logic programming is the representation of knowledge. It is established that the Horn clause is subject to interpretation in terms of procedure and vice versa. It is also established that Procedures related to goal-reduction can also be identified as Horn clauses.

In addition to this, backward reasoning also means that the programs combine the two different ways of procedural as well as declarative knowledge representation ideas. Besides this, the process of including the concept of negation as a failure actually means that logical programming runs more effectively on non-monotonic logic.
No matter how many comparisons have been drawn with classical logic in terms of the lucidity of the present framework, it is seen that the concept of negation as a failure as well that of the Horn clause has proved to be expressive beyond repair.

For instance, these current concepts helped in establishing a natural representation of the cause and effect relationship. It takes into account the ideas of common sense. Most importantly, this cause and effect relationship has been effectively formulated by not only the situation calculus but also the event calculus. Besides this, it is also compatible with the language of legislation which is relatively semi-formal in nature.

Execution of Logic Programming

The implementation of a programming language is a process used to execute computer programs. A program consists of many instructions. Every instruction of the program is to be executed for a specific task. System run here is mainly two types of methods for the execution of programming language interpretation and compilation. A contemporary Programming language such as JAVA provides many enhanced concepts including memory management automatic, an effective real-time compilation.

Programming languages use different approaches to carry out the process. In this programming, rules are to be written in the figure of clauses. This programming language uses mathematical logic to solve problems. It can be interpreted utilizing the main two concepts: truth as well as a deduction. Truth derives the computation in the program is either true or false. Logical deduction examines that the logical clause is whether the outcome of the program or not. Most importantly, all the logic programming languages are of the same operational meaning.

The programs are themselves instructions to be executed. The instruction should be interpreted as a logical statement as well as a clause. The outcome of this execution is the logical result of the computation.  

In the case of ASP and Datalog, these programs have a single declarative reading. Their implementation is completed by a model generator or proof procedure. The programmers use this method to examine the correctness of the program. In the case of Datalog programming, it gives accessibility to the deductive database in either batch or imperative mode. In the case of batch mode, a program reads through the Datalog program as well as prints the result to the query and afterward exists.

Besides this, in the situation of interactive mode, the program handles all lines of text. It reads and prints the outcome to query after that without delay takes more inputs. On the other hand, in the case of Prolog programs, logic language consists of procedural interpretation like the goal reduction process. In Prolog programming, execution is initiated with a single goal known as query created by users. It tries to get a resolution for the negated query. The resolution approach used by Prolog is known as SLD resolution. If the case of a negated query is not resolute, it follows that particular query with proper changeable binding in position.

This is the logical outcome of the program. Every generated changeable binding is reported to the user. Afterward, the query is considered as successful.  If some goals fail during the implementation of the program, every changeable binding is undone. With the alternative choice, the implementation process continues. However, logic programming based techniques could be used to convert a logical program into more efficient and logically comparable programs.

Advantages of Logic Programming

The programming language is the formally formed language that is designed to converse the instruction into the system. Logic programming can be utilized in creating the program for controlling the actions of machines as well as express algorithms. There are main languages including Prolog, answer set programming and data log. Using logical language provides advantages in various ways.

This type of programming is very reliable. This is best for problem-solving tasks. It can develop rapidly since it uses right and wrong statements, not objects. In logic programming language, the data can be represented both intentionally as well as extensionally. Intentional representation could produce associated representation such as adjacency directory. This is a trouble-free acquiring of the data elements. These could be consequent energetically from pattern rules. Most importantly, these types of languages are considered as high-level languages. They implement the logic of computation instead of mechanics.

Logic programming follows a sound outline of mechanism and well management of memory. Besides, this type of programming language is ideal to express algorithms as well as complex ideas. This programming is made up of simple codes that are easy to read as well as debug. It is utilized to express information simply. They are not dependent on the execution of the program for making it more compressed or flexible or understandable. It makes information separated from use. The architecture of the machine can be changed without any change in the program as well as their fundamental codes.

It could be changed as well as extended for supporting special forms of information such as high order information. In addition to this, Logic programming is used in the non-computational process depending on reasoning and exact way of expression. This is easier to manage because it has fewer mistakes compared to another traditional language. This is a good method to write programs which starts very quickly. Since the whole thing is to tie up in dependencies, the exact necessary code runs when it is required.

Limitations of Logic Programming

Logic programming is limited to particular types of problems for solving. The execution of this program can be slow and with an unconventional method such as using true-false statement, all the problems cannot be solved. The predicates are of rigid nature as well as not readable quickly. This is used by a fewer application. There is not any proper way available to represent computational concepts.

The poor facilities to support arithmetic have a negative effect on programmers. Programmers always prefer the visible operational behavior of machines and dynamic control on moving parts.  The datalog programming does not allow complicated terms such as the argument of predicates. It imposes firm limitations on the usage of recursions as well as negation. It requires each variable appeared at top of the clause must appear in non-arithmetic literal. In addition to this, it also requires a clause that appeared in negative literal must appear in a positive literal of the clause.

In the case of Prolog programming, it tempts to write a clause that appears rationally correct but they would not run. Input, as well as output, is not easy. In this programming, the part of data structure cannot be re-assigned making it impossible to execute array. The exact manner to write the predicates is expected to be effective you must know when to optimize the predicates.  Because of the lack of functional documents, predicates may become burdensome. For more details you can also check Assignment Help Australia.

Tagged , ,