Embedded pushdown automaton
An **Embedded Pushdown Automaton (EPDA)** is a specific type of computational model that extends the capabilities of traditional pushdown automata (PDA). To understand what an EPDA is, it's helpful to first review some concepts related to pushdown automata. ### Pushdown Automaton (PDA) A **pushdown automaton** is a type of automaton that employs a stack as its primary data structure, allowing it to recognize a class of languages known as context-free languages.
Evolution in a variable environment refers to the concept that the conditions and challenges faced by organisms can change over time, influencing the process of natural selection and evolutionary adaptations. In such environments, organisms must be able to adapt not only to the current conditions but also to potential future changes in their habitat. Key aspects of evolution in a variable environment include: 1. **Phenotypic Plasticity**: This is the ability of an organism to alter its physical or behavioral traits in response to changes in the environment.
Extended finite-state machine
An Extended Finite State Machine (EFSM) is a computational model that extends the capabilities of a traditional finite state machine (FSM). While a traditional FSM consists of a finite number of states and transitions between those states based on input symbols, an EFSM incorporates additional features that provide greater expressive power.
FRACTRAN
FRACTRAN is a minimalistic programming language invented by mathematician John Conway. It is designed to demonstrate how computation can be implemented using a simple set of rules involving fractions. The primary concept of FRACTRAN is to execute a series of operations on an integer using a list of fractions. The way FRACTRAN works is as follows: 1. You start with a positive integer (usually 1). 2. You have a predefined list of fractions.
Interaction nets
Interaction nets are a computational model introduced by Jean-Yves Girard in the context of proof theory and the semantics of programming languages. They are a form of structured representation for computations that is based on the concept of interaction between entities, where the entities can represent various computational constructs such as variables, functions, or data.
Kahn process networks
Kahn Process Networks (KPN) is a model used in computer science and systems engineering for concurrent computation. It was introduced by Gilles Kahn in the 1970s as a way to represent and reason about the flow of information between processes in a network. Here are the key features and concepts related to Kahn Process Networks: 1. **Processes and Ports**: In a KPN, processes can be thought of as independent entities that execute computations.
Krivine machine
The Krivine machine is a computational model used to implement and understand lazy evaluation, particularly in the context of functional programming languages. It was introduced by a computer scientist named Jean-Pierre Krivine in the context of the implementation of the lambda calculus. ### Key Features of the Krivine Machine: 1. **Lazy Evaluation**: The Krivine machine is designed to efficiently handle lazy evaluation, which means that expressions are only evaluated when their values are needed.
Lambda calculus
Lambda calculus is a formal system in mathematical logic and computer science for expressing computation based on function abstraction and application. It was developed by Alonzo Church in the 1930s as part of his work on the foundations of mathematics. The key components of lambda calculus include: 1. **Variables**: These are symbols that can stand for values. 2. **Function Abstraction**: A lambda expression can describe anonymous functions.
Lazy linear hybrid automaton
A Lazy Linear Hybrid Automaton (LLHA) is an extension of traditional hybrid automata, which are mathematical models used to represent systems that can exhibit both discrete and continuous behaviors. Hybrid automata combine finite state machines (for discrete behaviors) with differential equations (for continuous behaviors), allowing them to model systems that switch between different modes of operation that involve both algebraic constraints and dynamic behavior.
Linear bounded automaton
A Linear Bounded Automaton (LBA) is a type of computational model that is a restricted form of a Turing machine. Specifically, an LBA operates on an input tape of finite length and is constrained to use only a bounded amount of tape space relative to the length of the input. Here are some key characteristics of LBAs: 1. **Tape Length**: An LBA has a tape whose length is linearly bounded by the length of the input.
LogP machine
The term "LogP" refers to a theoretical model for parallel computation characterized by four parameters: **L** (latency), **o** (overlap), **g** (granularity), and **P** (number of processors). It was introduced by William J. Dally and Peter Hanrahan in the early 1990s to address some limitations of earlier parallel computing models.
Markov algorithm
A Markov algorithm is a specific type of computational model that is based on the principles of Markov processes and is used to define computations through a set of rules or operations on strings. It was developed by the Soviet mathematician Andrey Markov and can be viewed as a precursor to more modern concepts in computer science and formal language theory. ### Key Features of Markov Algorithms: 1. **String Manipulation**: Markov algorithms operate on strings of symbols.
Mealy machine
A **Mealy machine** is a type of finite state machine (FSM) that produces outputs based on both its current state and the current input symbol. Named after George H. Mealy, it is one of the two fundamental types of finite state machines, the other being the Moore machine. ### Key Characteristics of a Mealy Machine: 1. **States**: The Mealy machine has a finite set of states.
Membrane computing
Membrane computing is a computational paradigm inspired by the biological processes of living cells, particularly the way that cell membranes control the interaction and organization of various cellular components. This field intersects computer science, mathematics, and biology, and it is particularly associated with the study of P systems. ### Key Concepts: 1. **P Systems**: At the core of membrane computing are P systems, which are abstract computational models that use multi-set rewriting rules applied to objects located within hierarchical structures (membranes).
Model of computation
A model of computation is a formal framework that describes how computations are performed. It outlines the rules and mechanisms by which processes or algorithms can be executed, providing a systematic way to study and analyze computational problems and their complexities. Different models of computation allow us to understand various computational paradigms and their capabilities and limitations.
NAR 1
"NAR 1" could refer to different contexts, so its meaning can vary based on the specific field or subject. One common interpretation in the context of real estate is related to the National Association of Realtors (NAR) and their various programs or designations. However, without additional context, it's hard to provide a precise answer.
NAR 2
"NAR 2" could refer to a few different things depending on the context. However, the most likely interpretation is that it refers to the **National Association of Realtors (NAR) 2.0**, which is a reference to modernized approaches and strategies within the real estate industry that the NAR might advocate. This includes advancements in technology, business practices, and ethical standards aimed at improving the real estate profession.
Nested stack automaton
A **nested stack automaton (NSA)** is a computational model that extends the capabilities of traditional pushdown automata (PDAs) by incorporating multiple stacks with a nested structure. While a standard PDA uses a single stack to manage a potentially infinite string of input symbols, a nested stack automaton can have a hierarchy of stacks that allows for more complex operations and relationships between the stacks.
Oblivious RAM
Oblivious RAM (ORAM) is a specialized cryptographic technique used to protect the privacy of memory access patterns in computing systems. The main goal of ORAM is to hide the access patterns of memory operations (reads and writes) from potential adversaries, thereby preventing them from inferring information about the data being accessed based on the sequence of memory operations. ### Key Concepts: 1. **Access Patterns**: When programs access memory, the sequence and nature of memory operations can reveal sensitive information.
One-instruction set computer
A One-Instruction Set Computer (OISC) is a theoretical type of computer architecture that has only one instruction in its instruction set. Although it may sound overly simplistic, this model is used to explore the limits of computing and understand the principles of computation. ### Key Characteristics of OISC: 1. **Single Instruction**: OISCs operate using only one fundamental instruction, which can typically be used to perform various operations through clever encoding and manipulation.