Artificial intelligence and data

Slowly changing dimension

A slowly changing dimension (SCD) is a data warehousing technique, introduced by Ralph Kimball in 1996, for managing changes to dimension attributes by overwriting, adding rows, or adding columns.

Small files problem: performance degradation in HDFS and lakehouse tables (Delta Lake, Apache Iceberg) when many tiny files overwhelm NameNode metadata, add per-file overhead, and require compaction (OPTIMIZE, auto compaction) into larger files.

Smart city

A smart city, also known as an intelligent city or U-city, is an urban area that uses data and sensors to improve public services, traffic, and energy use.

Smoothed analysis

Smoothed analysis is a framework for analyzing algorithms that measures their performance on inputs perturbed by small random noise, introduced by Spielman and Teng in 2001.

SMOTE

SMOTE, the Synthetic Minority Over-sampling Technique, is a machine learning preprocessing method that balances imbalanced classification datasets by generating synthetic minority-class examples through interpolation, introduced by Chawla and colleagues in 2002.

Snake optimizer

The snake optimizer, also known as snake optimization, is a swarm-based metaheuristic for continuous optimization introduced in 2022, modeling snake foraging, fighting, and mating behavior to search for optimal solutions.

Snapshot compressive imaging

Snapshot compressive imaging is a computational imaging method that captures hyperspectral images or videos in a single 2D snapshot, recovering the full data cube by algorithm.

SNOMED CT

SNOMED CT (Systematized Nomenclature of Medicine Clinical Terms) is a multilingual clinical terminology giving each clinical meaning a unique numeric identifier, first released in January 2002 with 278,000 concepts.

SNOPT

SNOPT (Sparse Nonlinear OPTimizer) is a software package for large-scale linear and nonlinear constrained optimization, developed by Philip Gill, Walter Murray, and Michael Saunders and widely used for aerospace trajectory optimization.

Snorkel AI

Snorkel AI, a 2019 Stanford AI Lab spinout led by CEO Alex Ratner, is a frontier AI data lab offering Snorkel Flow programmatic labeling, weak supervision datasets, and RL environments; it raised $350M at a $3.5B valuation in 2026.

Snowflake Cortex

Snowflake Cortex is Snowflake's suite of LLM-based AI features, including Cortex Analyst, AI Functions, Search, Agents, and the Cortex Code coding agent (now Snowflake CoCo), running inside Snowflake's governed security perimeter.

Snowflake Inc.

Snowflake Inc., also known as Snowflake Computing, is an American cloud data platform company founded in 2012, offering data warehousing, data sharing, and AI services.

Snowflake schema

The snowflake schema is a data warehouse design, a variation of the star schema, in which normalized dimension tables are split into sub-dimension tables, reducing redundancy but adding query joins.

Snowplow (company)

Snowplow is a London-based behavioral data and customer data infrastructure company founded in 2012 by Alex Dean and Yali Sassoon. It offers event pipelines, Snowplow Signals, and source-available licensing from 2024, distinct from snow-clearing equipment makers.

Soar (cognitive architecture)

Soar is a cognitive architecture, developed by John Laird at the University of Michigan, that models human cognition and intelligent agents through production rules and chunking.

Sobel operator

The Sobel operator, also known as the Sobel-Feldman operator, is a discrete differentiation filter used in image processing for edge detection via two 3×3 convolution kernels.

Social force model

The social force model is a pedestrian simulation method introduced by Dirk Helbing and Péter Molnár in 1995, treating crowd motion as social forces and reproducing lane formation.

Social media sentiment analysis

Social media sentiment analysis is a natural language processing method that detects opinions in posts, classifying them as positive, negative, or neutral, with lexicon, machine learning, and transformer approaches.

Social network analysis

Social network analysis (SNA) studies social structure by mapping relationships among actors, such as people, organizations, or countries, rather than treating individuals as independent units.

Social Science Research Network

The Social Science Research Network, known as SSRN, is an open-access preprint repository founded in 1994 in Rochester, New York, and owned by Elsevier since 2016.

Social Security Death Index

The Social Security Death Index (SSDI) is a publicly searchable genealogical index of deceased Americans, built by commercial services from the Social Security Administration's Death Master File.

Social Security number

A Social Security number (SSN) is a nine-digit number issued by the U.S. Social Security Administration, created in 1936 to track workers' earnings and now a nearly universal U.S. identifier.

Social-GAN

Social-GAN is a deep learning model combining a GAN with LSTMs to predict multiple socially plausible pedestrian paths, published by Gupta and colleagues at CVPR in 2018.

Social-LSTM

Social-LSTM is a recurrent neural network architecture for predicting pedestrian trajectories in crowded spaces, introduced at CVPR 2016, assigning each person an LSTM linked through a Social pooling layer.

Soda Core

Soda Core (SodaCL) is an open-source Python library and CLI by Soda of Brussels for data quality testing and, since v4 (January 2026, Elastic License 2.0), data contracts, running YAML-defined checks against 18+ sources including Snowflake, Databricks, and BigQuery.

Soft clustering

Soft clustering is a family of clustering algorithms that assign each data point a degree of membership in every cluster instead of a single hard label.

Soft-decision decoding

Soft-decision decoding is a family of error-correction methods that pass each received symbol's reliability to the decoder, gaining roughly 1.5 to 2.3 dB over hard decisions.

Solidatus

Solidatus (Threadneedle Software Holdings) is a London data lineage and metadata management platform launched in 2017, known for bi-temporal version control, column-level lineage, and the AI Lineage Assistant, serving banks such as HSBC, BNY, and LSEG for BCBS 239, DORA, and EU AI Act compliance.

Sonification

Sonification is the use of non-speech audio to convey information, converting data into sound so that patterns and relations in the data can be perceived by listening.