Artificial intelligence and data

Shuffle (distributed computing)

Shuffle is the all-to-all redistribution of intermediate data between map and reduce tasks in frameworks like Spark and MapReduce, enabling joins, aggregations, and sorts. Its Mapper × Reducer block count and quadratic growth make it the costliest distributed primitive.

Siamese neural network

A Siamese neural network runs two inputs through identical weight-sharing subnetworks and compares the outputs, learning whether inputs are similar rather than which class they belong to.

Sifflet

Sifflet is a Paris-based data observability SaaS platform founded in 2021 by Salma Bakouk and the Fathallah brothers, offering data quality monitoring, lineage, catalog, and AI agents; backed by EQT Ventures and Mangrove.

Sigma Computing

Sigma Computing is a San Francisco company founded in 2014 by Rob Woollen and Jason Frantz whose Sigma platform is a spreadsheet UI on cloud data warehouses like Snowflake and Databricks, compiling formulas into live SQL with writeback, AI apps, and embedding.

Sign language recognition

Sign language recognition (SLR) is the automatic identification of sign language content from video or sensor data by a computer, spanning more than 300 distinct sign languages.

Signal averaging

Signal averaging is a signal processing technique that averages repeated measurements of a time-locked response so uncorrelated noise cancels, improving the signal-to-noise ratio in EEG, ECG, and spectroscopy.

Signal separation

Signal separation, also called blind source separation (BSS), is a family of signal processing methods that recover individual source signals from observed mixtures without knowing the mixing process.

Signature verification

Signature verification is the process of deciding whether a signature is genuine or forged, done by forensic document examiners and by automated biometric systems used in banking.

Silhouette (clustering)

The silhouette, or silhouette score, is a cluster validity index introduced by Peter J. Rousseeuw in 1987 that measures how well each object fits its cluster versus the nearest other cluster.

SIMBAD

SIMBAD, the Set of Identifications, Measurements and Bibliography for Astronomical Data, is an online database of astronomical objects outside the Solar System, run by the CDS in Strasbourg, France.

SimCLR

SimCLR is a self-supervised learning method that trains an image encoder by contrasting two augmented views of the same image, reported by Ting Chen and colleagues in 2020.

SIMPLE algorithm

The SIMPLE algorithm (Semi-Implicit Method for Pressure-Linked Equations) is an iterative pressure-correction method for computing incompressible fluid flows, introduced by Patankar and Spalding in 1972 and still standard in CFD software.

Simplex algorithm

The simplex algorithm, also called the simplex method, is a pivoting method for solving linear programs by moving between vertices of the feasible polyhedron. George Dantzig formulated it in 1947.

Simpson's rule

Simpson's rule, also called Simpson's formula, is a Newton-Cotes method that approximates a definite integral by fitting a parabola through three equally spaced points of the integrand.

Simulation

A simulation is a program or experiment on a model that imitates the behavior of a real system, used in physics, biology, economics, and engineering where analytical solutions are impractical.

Simultaneous localization and mapping

Simultaneous localization and mapping, also known as concurrent mapping and localization or SLAM, is the computational problem of building a map of an unknown environment while tracking a robot's position within it.

Simultaneous machine translation

Simultaneous machine translation, also known as SiMT or real-time translation, is the task of translating a sentence from partial input before the speaker finishes, trading some quality for lower latency.

Sine cosine algorithm

The sine cosine algorithm (SCA) is a gradient-free metaheuristic for continuous optimization that updates candidate solutions using sine and cosine fluctuations toward the best solution found so far.

Singer (data integration specification)

Singer is an open-source data integration specification, also called the Singer spec, defining JSON message exchange between extractor taps and loader targets. Created by Stitch around 2016-2017; spec v0.3.0 defines SCHEMA, RECORD, STATE messages over stdout.

Single source of truth

Single source of truth (SSOT): a data management principle naming one authoritative system per business fact, with all other systems holding copies. Covers implementation patterns, MDM relationship, risks, and data mesh alternatives.

SingleStore

SingleStore (formerly MemSQL, founded 2011, Y Combinator W11) is a distributed SQL HTAP database combining in-memory rowstore and on-disk columnstore; MySQL-compatible, C++, owned by Vector Capital since October 2025.

Sisense

Sisense is a business intelligence and analytics software company founded in Israel in 2004 and headquartered in New York, focused on embedding dashboards and AI-powered insights into other companies' products.

Situation calculus

The situation calculus is a logical formalism in artificial intelligence for representing changing worlds, best known through Ray Reiter's solution to the frame problem and the Golog language.

Skeleton-based action recognition

Skeleton-based action recognition classifies human actions from time sequences of body-joint coordinates rather than raw video. It is robust to lighting and background changes, efficient, and privacy-friendly.

Skip list

A skip list is a probabilistic data structure for sorted keys that supports search, insertion, and deletion in expected logarithmic time, introduced by William Pugh in 1990 and used in Redis and LevelDB.

Skynet (Terminator)

Skynet, the Skynet Global Defense Network, is a fictional military AI in the Terminator franchise, first appearing in James Cameron's 1984 film The Terminator and becoming a cultural shorthand for dangerous AI.

Slaughterbots

Slaughterbots is a 7-minute 2017 short film by the Future of Life Institute, directed by Stewart Sugg, dramatizing AI-driven micro-drone swarms killing targeted humans; it coined the popular term for lethal autonomous weapons and premiered at the UN CCW.