A deductive database is a database system that can make deductions (i.e. conclude additional facts) based on rules and facts stored in its database. Datalog is the language typically used to specify facts, rules and queries in deductive databases. Deductive databases have grown out of the desire to combine logic programming with relational databases to construct systems that support a powerful formalism and are still fast and able to deal with very large datasets. Deductive databases are more expressive than relational databases but less expressive than logic programming systems such as Prolog. In recent years, deductive databases have found new application in data integration, information extraction, networking, program analysis, security, and cloud computing. [1]
Deductive databases reuse many concepts from logic programming; rules and facts specified in Datalog look very similar to those written in Prolog, but there are some important differences:
Logic programming is a programming, database and knowledge-representation and reasoning paradigm which is based on formal logic. A program, database or knowledge base in a logic programming language is a set of sentences in logical form, expressing facts and rules about some problem domain. Major logic programming language families include Prolog, Answer Set Programming (ASP) and Datalog. In all of these languages, rules are written in the form of clauses:
Prolog is a logic programming language associated with artificial intelligence and computational linguistics.
Procedural programming is a programming paradigm, derived from imperative programming, based on the concept of the procedure call. Procedures simply contain a series of computational steps to be carried out. Any given procedure might be called at any point during a program's execution, including by other procedures or itself. The first major procedural programming languages appeared c. 1957–1964, including Fortran, ALGOL, COBOL, PL/I and BASIC. Pascal and C were published c. 1970–1972.
The relational model (RM) is an approach to managing data using a structure and language consistent with first-order predicate logic, first described in 1969 by English computer scientist Edgar F. Codd, where all data is represented in terms of tuples, grouped into relations. A database organized in terms of the relational model is a relational database.
Structured Query Language (SQL) is a domain-specific language used in programming and designed for managing data held in a relational database management system (RDBMS), or for stream processing in a relational data stream management system (RDSMS). It is particularly useful in handling structured data, i.e., data incorporating relations among entities and variables.
Planner is a programming language designed by Carl Hewitt at MIT, and first published in 1969. First, subsets such as Micro-Planner and Pico-Planner were implemented, and then essentially the whole language was implemented as Popler by Julian Davies at the University of Edinburgh in the POP-2 programming language. Derivations such as QA4, Conniver, QLISP and Ether were important tools in artificial intelligence research in the 1970s, which influenced commercial developments such as Knowledge Engineering Environment (KEE) and Automated Reasoning Tool (ART).
In computer science, declarative programming is a programming paradigm—a style of building the structure and elements of computer programs—that expresses the logic of a computation without describing its control flow.
In aspect-oriented programming, a pointcut is a set of join points. Pointcut specifies where exactly to apply advice, which allows separation of concerns and helps in modularizing business logic. Pointcuts are often specified using class names or method names, in some cases using regular expressions that match class or method name. Different frameworks support different Pointcut expressions; AspectJ syntax is considered as de facto standard. Frameworks are available for various programming languages like Java, Perl, Ruby, and many more which support pointcut.
A query language, also known as data query language or database query language (DQL), is a computer language used to make queries in databases and information systems. A well known example is the Structured Query Language (SQL).
Object–role modeling (ORM) is used to model the semantics of a universe of discourse. ORM is often used for data modeling and software engineering.
Datalog is a declarative logic programming language. While it is syntactically a subset of Prolog, Datalog generally uses a bottom-up rather than top-down evaluation model. This difference yields significantly different behavior and properties from Prolog. It is often used as a query language for deductive databases. Datalog has been applied to problems in data integration, networking, program analysis, and more.
Database theory encapsulates a broad range of topics related to the study and research of the theoretical realm of databases and database management systems.
Object–relational impedance mismatch creates difficulties going from data in relational data stores to usage in domain-driven object models. Object-orientation (OO) is the default method for business-centric design in programming languages. The problem lies in neither relational nor OO, but in the conceptual difficulty mapping between the two logic models. Both are logical models implementable differently on database servers, programming languages, design patterns, or other technologies. Issues range from application to enterprise scale, whenever stored relational data is used in domain-driven object models, and vice versa. Object-oriented data stores can trade this problem for other implementation difficulties.
Fril is a programming language for first-order predicate calculus. It includes the semantics of Prolog as a subset, but takes its syntax from the micro-PROLOG of Logic Programming Associates and adds support for fuzzy sets, support logic, and metaprogramming.
A deductive language is a computer programming language in which the program is a collection of predicates ('facts') and rules that connect them. Such a language is used to create knowledge based systems or expert systems which can deduce answers to problem sets by applying the rules to the facts they have been given. An example of a deductive language is Prolog, or its database-query cousin, Datalog.
Semmle Inc is a code-analysis platform; Semmle was acquired by GitHub on 18 September 2019 for an undisclosed amount. Semmle's LGTM technology automates code review, tracks developer contributions, and flags software security issues. The LGTM platform leverages the CodeQL query engine to perform semantic analysis on software code bases. GitHub aims to integrate Semmle technology to provide continuous vulnerability detection services. In November 2019, use of CodeQL was made free for research and open source. CodeQL either shares a direct pedigree with .QL (dot-que-ell), which derives from the Datalog family tree, or is an evolution of similar technology.
In database theory, a conjunctive query is a restricted form of first-order queries using the logical conjunction operator. Many first-order queries can be written as conjunctive queries. In particular, a large part of queries issued on relational databases can be expressed in this way. Conjunctive queries also have a number of desirable theoretical properties that larger classes of queries do not share.
Ciao is a general-purpose programming language which supports logic, constraint, functional, higher-order, and object-oriented programming styles. Its main design objectives are high expressive power, extensibility, safety, reliability, and efficient execution.
The following is provided as an overview of and topical guide to databases:
The Vadalog system is a Knowledge Graph Management System (KGMS) that offers a language for performing complex logic reasoning tasks over knowledge graphs. At the same time, Vadalog delivers a platform to support the entire spectrum of data science tasks: data integration, pre-processing, statistical analysis, machine learning, algorithmic modeling, probabilistic reasoning and temporal reasoning. Its language is based on an extension of the rule-based language Datalog, Warded Datalog±, a high-performance language using an aggressive termination control strategy. Vadalog can support the entire spectrum of data science activities and tools. The system can read from and connect to multiple sources, from relational databases, such as PostgreSQL and MySQL, to graph databases, such as Neo4j, as well as make use of machine learning tools, and a web data extraction tool, OXPath. Additional Python libraries and extensions can also be easily integrated into the system.
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