Q-function - A Q-function estimates how good it is to take a particular action in a particular situation, measured as the total reward an agent can expect to collect...
Q-learning - Q-learning is a model-free reinforcement learning method that updates estimates of the long-term value of taking actions in states.
Q-Q plot - A Q-Q plot, or quantile-quantile plot, compares corresponding quantiles of two distributions.
Q-systems - Q-systems are a historical language-processing formalism developed by Alain Colmerauer for representing and transforming linguistic structures through...
Q-value (statistics) - A q-value is a measure of statistical significance designed for multiple hypothesis testing.
Quadratic classifier - A quadratic classifier assigns categories using a decision function that includes second-degree terms, such as squared features and products of pairs of...
Quadratic function - A quadratic function is a function built from constant, linear and second-degree terms. For a real vector x, it can be written f(x)=xᵀQx+bᵀx+c.
Quadratic probing - Quadratic probing is a collision-resolution method for an open-addressed hash table.
Quadratic programming - Quadratic programming is optimization with a quadratic objective function and linear equality or inequality constraints.
Quadratic unconstrained binary optimization - Quadratic unconstrained binary optimization, usually abbreviated QUBO, is a problem formulation that minimizes a quadratic objective over variables...
Quadrature mirror filter - A quadrature mirror filter, or QMF, is a filter used in a filter-bank arrangement that separates a signal into complementary frequency bands.
Qualification problem - The qualification problem is the difficulty of specifying all the conditions required for a real-world action to produce its intended result.
Qualitative data - Qualitative data describe types, qualities, or categories rather than measured amounts or counts.
Qualitative physics - Qualitative physics is an area of AI concerned with representing and reasoning about physical systems using meaningful qualitative distinctions, such as...
Qualitative probabilistic networks - Qualitative probabilistic networks represent probabilistic relationships using qualitative constraints, such as whether one variable has a positive...
Quality of Data - Quality of Data, or QoD, here refers to a research approach for expressing required consistency of replicated data through limits on divergence.
Quantification - Quantification expresses how a statement applies to members of a domain, such as all objects, at least one object, or a specified number of objects.
Quantile - A quantile usually means a value marking a specified position in an ordered distribution, such as the median or the 90th percentile.
Quantile bucketing - Quantile bucketing divides a numerical feature into intervals intended to contain the same, or approximately the same, number of observations in a reference...
Quantile Regression - Quantile regression models a chosen quantile of an outcome conditional on explanatory variables.
Quantile regression averaging - Quantile regression averaging, or QRA, combines forecasts by using them as inputs to a quantile regression model.
Quantitative data - Quantitative data represent measured amounts or counts expressed numerically.
Quantitative forecasting - Quantitative forecasting uses numerical information and explicit mathematical or statistical procedures to estimate future outcomes.
Quantization error - Quantization error is the difference between an original value and the discrete value used to represent it after quantization.
Quantum artificial life - Quantum artificial life is a research area that constructs quantum models inspired by processes associated with living systems, such as inheritance...
Quantum natural language processing - Quantum natural language processing, or QNLP, is research into language-processing models designed to use quantum computation.
Quantum neural network - A quantum neural network is a learning model that uses quantum operations in a network-like or trainable computational structure.
Quartile - A quartile is a cut point in an ordered distribution associated with quarters of its cumulative probability.
Quasi-logical form - A quasi-logical form, or QLF, is a structured representation of sentence meaning that can leave some interpretation choices unresolved.
Quasi-Monte Carlo integration - Quasi-Monte Carlo integration estimates an integral by averaging a function over deliberately well-distributed points rather than independent random points.
Quasi-stationary distribution - A quasi-stationary distribution is a probability distribution over a process's nonabsorbing states that remains unchanged when the process starts with that...
Query by committee - Query by committee is an active-learning strategy that selects examples for labeling by examining disagreement among several plausible models.
Query Engines - Query engines are software components that interpret requests for data, plan how to carry out those requests, and execute operations that produce results.
Query language - A query language is a language for expressing requests for information from a data system.
Query-level feature - A query-level feature is a measurable property of a search query, rather than a property of an individual candidate document or of the match between the two.
Query likelihood model - The query likelihood model is an information-retrieval approach that ranks documents by how likely each document's language model would be to generate the...
Query understanding - Query understanding is the process of interpreting a search request so that a system can better identify the information or result the user is seeking.
Querying - Querying is the process of asking a data source or knowledge system a precisely expressed question and obtaining results according to its rules.
Question answering - Question answering, or QA, is an AI task in which a system produces an answer to a user's question.
Questionnaire error - Questionnaire error is the part of survey measurement error attributable to a questionnaire's wording, structure, or form.
Quickprop - Quickprop is a neural-network optimization algorithm introduced by Scott Fahlman that uses successive gradient information to estimate larger, useful weight...
Quiescence search - Quiescence search is a selective extension of game-tree search that examines unstable positions beyond the normal cutoff before evaluating them.