Computer programs in the context of Memoization

In computing, an interpreter is software that executes source code without first compiling it to machine code. An interpreted runtime environment differs from one that processes CPU-native executable code which requires translating source code before executing it. An interpreter may translate the source code to an intermediate format, such as bytecode. A hybrid environment may translate the bytecode to machine code via just-in-time compilation, as in the case of .NET and Java, instead of interpreting the bytecode directly.

Before the widespread adoption of interpreters, the execution of computer programs often relied on compilers, which translate and compile source code into machine code. Early runtime environments for Lisp and BASIC could parse source code directly. Thereafter, runtime environments were developed for languages (such as Perl, Raku, Python, MATLAB, and Ruby), which translated source code into an intermediate format before executing to enhance runtime performance.

In computer science, in particular in knowledge representation and reasoning and metalogic, the area of automated reasoning is dedicated to understanding different aspects of reasoning. The study of automated reasoning helps produce computer programs that allow computers to reason completely, or nearly completely, automatically. Although automated reasoning is considered a sub-field of artificial intelligence, it also has connections with theoretical computer science and philosophy.

The most developed subareas of automated reasoning are automated theorem proving (and the less automated but more pragmatic subfield of interactive theorem proving) and automated proof checking (viewed as guaranteed correct reasoning under fixed assumptions). Extensive work has also been done in reasoning by analogy using induction and abduction.

A computer virus is a type of malware that, when executed, replicates itself by modifying other computer programs and inserting its own code into those programs. If this replication succeeds, the affected areas are then said to be "infected" with a computer virus, a metaphor derived from biological viruses.

Computer viruses generally require a host program. The virus writes its own code into the host program. When the program runs, the written virus program is executed first, causing infection and damage. By contrast, a computer worm does not need a host program, as it is an independent program or code chunk. Therefore, it is not restricted by the host program, but can run independently and actively carry out attacks.

Computational science, also known as scientific computing, technical computing or scientific computation (SC), is a division of science, and more specifically the computer sciences, which uses advanced computing capabilities to understand and solve complex physical problems in science. While this typically extends into computational specializations, this field of study includes:

• Algorithms (numerical and non-numerical): mathematical models, computational models, and computer simulations developed to solve sciences (e.g, physical, biological, and social), engineering, and humanities problems
• Computer hardware that develops and optimizes the advanced system hardware, firmware, networking, and data management components needed to solve computationally demanding problems
• The computing infrastructure that supports both the science and engineering problem solving and the developmental computer and information science

In practical use, it is typically the application of computer simulation and other forms of computation from numerical analysis and theoretical computer science to solve problems in various scientific disciplines. The field is different from theory and laboratory experiments, which are the traditional forms of science and engineering. The scientific computing approach is to gain understanding through the analysis of mathematical models implemented on computers. Scientists and engineers develop computer programs and application software that model systems being studied and run these programs with various sets of input parameters. The essence of computational science is the application of numerical algorithms and computational mathematics. In some cases, these models require massive amounts of calculations (usually floating-point) and are often executed on supercomputers or distributed computing platforms.

George Armitage Miller (February 3, 1920 – July 22, 2012) was an American psychologist who was one of the founders of cognitive psychology, and more broadly, of cognitive science. He also contributed to the birth of psycholinguistics. Miller wrote several books and directed the development of WordNet, an online word-linkage database usable by computer programs. He authored the paper, "The Magical Number Seven, Plus or Minus Two," in which he observed that many different experimental findings considered together reveal the presence of an average limit of seven for human short-term memory capacity. This paper is frequently cited by psychologists and in the wider culture. Miller won numerous awards, including the National Medal of Science.

Miller began his career when the reigning theory in psychology was behaviorism, which eschewed the study of mental processes and focused on observable behavior. Rejecting this approach, Miller devised experimental techniques and mathematical methods to analyze mental processes, focusing particularly on speech and language. Working mostly at Harvard University, MIT and Princeton University, he went on to become one of the founders of psycholinguistics and was one of the key figures in founding the broader new field of cognitive science, c. 1978. He collaborated and co-authored work with other figures in cognitive science and psycholinguistics, such as Noam Chomsky. For moving psychology into the realm of mental processes and for aligning that move with information theory, computation theory, and linguistics, Miller is considered one of the great twentieth-century psychologists. A Review of General Psychology survey, published in 2002, ranked Miller as the 20th most cited psychologist of that era.

In computer programming, a programming language implementation is a system for executing computer programs. There are two general approaches to programming language implementation:

• Interpretation: The program is read as input by an interpreter, which performs the actions written in the program.
• Compilation: The program is read by a compiler, which translates it into some other language, such as bytecode or machine code. The translated code may either be directly executed by hardware or serve as input to another interpreter or another compiler.

In addition to these two extremes, many implementations use hybrid approaches such as just-in-time compilation and bytecode interpreters.