3,135 articles
Query expansion
Query expansion is an information retrieval technique that adds terms of similar meaning to a user's query, so search retrieves documents the original keywords would have missed.
Query federation
Query federation executes a single query across multiple autonomous data sources through one interface, leaving data in place instead of copying it (data virtualization). Key systems include Trino, Denodo, Dremio, Teiid, and FedX; standards include SPARQL 1.1 Federated Query.
Query language
A query language, also known as a database query language, is a computer language for requesting information from a database, the dominant example being SQL.
Query optimization
Query optimization, also called query planning, is the process by which a database management system chooses the fastest or cheapest execution plan for a SQL query.
Query optimizer
A query optimizer is the component of a database management system that chooses an efficient execution plan for a SQL query, selecting join orders, algorithms, and access paths by cost.
Query plan
A query plan, also known as a query execution plan or execution plan, is the tree of scan, join, sort, and aggregate operators a database engine runs for a SQL statement.
Question answering
Question answering (QA) is a natural language processing task in which a computer returns a direct answer to a question instead of a list of documents.
Queue (abstract data type)
A queue is an abstract data type that stores items in first-in, first-out order, adding them at the rear with enqueue and removing them from the front with dequeue.
Queueing model
A queueing model is a mathematical representation of systems where customers arrive, wait in line, and are served, used to predict congestion, queue lengths, and waiting times.
Quickselect
Quickselect, also called Hoare's selection algorithm, is a selection algorithm that finds the k-th smallest element of an unordered array. Devised by Tony Hoare, it runs in expected linear time.
Quicksort
Quicksort, also called partition-exchange sort, is a divide-and-conquer sorting algorithm that partitions an array around a pivot and recursively sorts each side. Tony Hoare invented it in 1959, and it typically runs fastest in practice.
R-CNN
R-CNN, short for Regions with CNN features, is an object detection algorithm introduced in 2013 by Ross Girshick and colleagues at UC Berkeley, applying CNNs to region proposals.
R-tree
An R-tree is a balanced tree index for multi-dimensional spatial data, proposed by Antonin Guttman in 1984 and built into database systems including PostgreSQL and SQLite.
Rabin–Karp algorithm
The Rabin–Karp algorithm, also known as Karp–Rabin, is a randomized string-searching algorithm published in 1987 that finds a pattern in text using a rolling hash.
Rademacher complexity
Rademacher complexity measures how well a class of functions can fit random noise, and enters generalization bounds relating a model's training error to its expected error on new data.
Radial basis function kernel
The radial basis function (RBF) kernel, also called the Gaussian kernel, measures the similarity of two points as a decreasing function of their Euclidean distance in machine learning.
Radial basis function network
A radial basis function network is a supervised-learning model, usually a two- or three-layer neural network, whose locally tuned hidden units approximate functions for classification and time-series prediction.
Radix sort
Radix sort is a non-comparison sorting algorithm that sorts integers or strings one digit at a time with stable passes, achieving linear time when digits are fixed.
Radix tree
A radix tree, also called a Patricia trie, is a space-saving tree data structure for storing strings, in which chains of single-child nodes are merged into one node.
Rahul Mangharam
Rahul Mangharam is a professor of electrical and systems engineering at the University of Pennsylvania, where he directs the Safe Autonomous Systems Lab and researches medical device safety.
Rainforest Connection
Rainforest Connection (RFCx) is an American nonprofit founded by physicist Topher White that uses solar-powered acoustic sensors and AI to detect illegal logging and poaching in real time.
Random forest
A random forest is an ensemble learning method for classification and regression that builds many randomized decision trees and predicts by averaging their outputs or majority vote.
Random neural network
The random neural network is a probabilistic neural network model in which neurons exchange excitatory and inhibitory spikes, introduced by Erol Gelenbe in 1989 and analyzed with queueing theory.
Random number generation
Random number generation is the production of numbers that lack a predictable pattern, drawn from physical processes or deterministic algorithms, and used in cryptography, Monte Carlo simulation, games, and testing.
Random optimization
Random optimization is a derivative-free stochastic direct-search method introduced by Matyás in 1965, which perturbs the current best point randomly and moves only on improvement.
Random projection
Random projection is a dimensionality reduction method that multiplies high-dimensional data by a randomly generated matrix, approximately preserving pairwise distances; the Johnson–Lindenstrauss lemma guarantees the needed target dimension.
Random search
Random search is an optimization method that samples candidate settings at random and returns the best one found, widely used for hyperparameter tuning in machine learning.
Random survival forest
A random survival forest (RSF) is an ensemble machine learning method that adapts Leo Breiman's random forests to survival analysis, predicting time-to-event outcomes from right-censored data using randomized survival trees.
Randomized algorithm
A randomized algorithm is an algorithm whose steps depend on random bits, split into Las Vegas algorithms, always correct, and Monte Carlo algorithms, which may err.
RankBrain
RankBrain is a machine-learning ranking system Google deployed in Search in 2015, its first deep learning system there, interpreting never-before-seen queries and ranking among Google's most important signals.