Artificial intelligence and data

Stack (abstract data type)

A stack, also called a push-down store, is an abstract data type where only the most recently added item may be removed, following last-in, first-out order.

Stacked ensemble learning

Stacked ensemble learning, or stacking, is a machine learning method in which a second-level meta-learner is trained on the predictions of several base models, introduced by David Wolpert in 1992.

Stacked ensemble model

Stacked ensemble model (stacking) is a supervised machine learning method that trains a second-level meta-model on the predictions of diverse base models to achieve higher accuracy.

Stacked generalization

Stacked generalization, or stacking, is an ensemble method in machine learning that trains a meta-learner on the outputs of base models, proposed by David Wolpert in 1992.

STag

STag is a square fiducial marker system for camera pose estimation, proposed in 2017, that minimizes pose jitter by refining the homography with a circular border.

Stance detection

Stance detection is a natural language processing task that classifies a text's attitude toward a supplied target as favorable, unfavorable, or neither, unlike general sentiment analysis.

Standard Contractual Clauses

Standard Contractual Clauses (SCCs) are pre-approved model clauses adopted by the European Commission that let companies transfer personal data outside the EEA without separate regulatory approval.

Stanford Artificial Intelligence Laboratory

The Stanford Artificial Intelligence Laboratory, known as SAIL, is Stanford University's AI research lab, founded in 1963 by John McCarthy and known for DENDRAL, the Stanford Cart, and robotics.

The star schema is a data warehouse design in which a central fact table holding numeric measurements joins directly to surrounding dimension tables, favored for fast analytical queries over the more normalized snowflake schema.

StarRocks

StarRocks is an open-source MPP OLAP database and lakehouse query engine forked from Apache Doris in 2020, donated to the Linux Foundation in 2023, with a vectorized engine, cost-based optimizer, and sub-second Iceberg analytics.

StarTree (company)

StarTree, Inc. is an American data-analytics company founded in 2019 in Mountain View, California, offering StarTree Cloud, a managed database service built on Apache Pinot.

State distillation (quantum computing)

State distillation is a quantum computing protocol that converts many noisy quantum states into fewer, higher-fidelity copies, enabling the non-Clifford gates required for universal fault-tolerant computation.

State-space search

State-space search is a family of algorithms in artificial intelligence that explore a problem's possible states to find a path from an initial state to a goal state.

Stateful stream processing

Stateful stream processing: continuous computation over unbounded data streams where operators maintain mutable state (windows, joins, aggregates). Key mechanisms are checkpointing, exactly-once recovery, LSM-tree or decoupled state backends, and transactional guarantees in systems like Flink and Kafka Streams.

Stationary wavelet transform

The stationary wavelet transform (SWT), also called the undecimated wavelet transform, is a variant of the discrete wavelet transform that omits downsampling, restoring translation invariance and improving denoising.

Statistical classification

Statistical classification, also called pattern classification, is the machine learning task of predicting which class an example belongs to, using methods such as logistic regression and support vector machines.

Statistical learning theory

Statistical learning theory, also known as statistical machine learning, is the mathematical framework studying when algorithms trained on finite samples perform well on new, unseen data.

Statistical machine translation

Statistical machine translation is an approach to machine translation that selects the most probable translation using probability models estimated from large collections of parallel text rather than hand-written rules.

Statistical relational learning

Statistical relational learning (SRL) is a branch of machine learning that combines probabilistic models with logical representations to learn and reason over structured, linked data such as networks and databases.

Statistical shape model

A statistical shape model is a computational method representing the variability of anatomical or object shapes, used to segment structures in medical images via a mean shape and principal modes of variation.

Stein variational gradient descent

Stein variational gradient descent (SVGD) is a particle-based variational inference algorithm introduced by Qiang Liu and Dilin Wang in 2016, which moves particles to approximate a target distribution.

Stemming

Stemming, or word stemming, is a text-normalization technique in natural language processing that cuts affixes off words so variants like eating and eat share a stem.

Stereo matching

Stereo matching is a computer vision method that matches pixels between two images of the same scene, producing a disparity map that converts to depth.

Stereo reconstruction

Stereo reconstruction is a computer vision method that estimates scene depth from a pair of images taken by calibrated cameras at different viewpoints, computing a disparity map convertible to depth values.

Stochastic gradient descent

Stochastic gradient descent (SGD), also called incremental gradient descent, is an iterative optimization algorithm that updates model parameters using a gradient estimated from a random subset of training data.

Stochastic neighbor embedding

Stochastic neighbor embedding (SNE) is a nonlinear probabilistic method for dimension reduction, introduced by Geoffrey Hinton and Sam Roweis at NIPS in 2002; its 2008 variant t-SNE is much more widely used.

Stochastic neural network

A stochastic neural network is a neural network in which units, weights, or connections are random variables, serving generative modeling, uncertainty estimation, and regularization; examples include Boltzmann machines and variational autoencoders.

Stored procedure

A stored procedure is a subroutine written in a procedural extension of SQL and stored inside a database server, executed there on request instead of ad hoc client statements.

Stream processing

Stream processing: continuous computation over unbounded data streams as records arrive, distinct from batch processing. Also called data stream processing. Key concepts: windows, watermarks, event time, state, exactly-once guarantees; systems include Flink, Kafka Streams, Spark Streaming.