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  2. Conjunctive query - Wikipedia

    en.wikipedia.org/wiki/Conjunctive_Query

    For the special case of conjunctive queries in which all relations used are binary, this notion corresponds to the treewidth of the dependency graph of the variables in the query (i.e., the graph having the variables of the query as nodes and an undirected edge {,} between two variables if and only if there is an atomic formula (,) or (,) in ...

  3. SQL - Wikipedia

    en.wikipedia.org/wiki/SQL

    SQL was initially developed at IBM by Donald D. Chamberlin and Raymond F. Boyce after learning about the relational model from Edgar F. Codd [12] in the early 1970s. [13] This version, initially called SEQUEL (Structured English Query Language), was designed to manipulate and retrieve data stored in IBM's original quasirelational database management system, System R, which a group at IBM San ...

  4. Multiple-scale analysis - Wikipedia

    en.wikipedia.org/wiki/Multiple-scale_analysis

    In mathematics and physics, multiple-scale analysis (also called the method of multiple scales) comprises techniques used to construct uniformly valid approximations to the solutions of perturbation problems, both for small as well as large values of the independent variables. This is done by introducing fast-scale and slow-scale variables for ...

  5. Scale analysis (statistics) - Wikipedia

    en.wikipedia.org/wiki/Scale_analysis_(statistics)

    The item-total correlation approach is a way of identifying a group of questions whose responses can be combined into a single measure or scale. This is a simple approach that works by ensuring that, when considered across a whole population, responses to the questions in the group tend to vary together and, in particular, that responses to no individual question are poorly related to an ...

  6. TimescaleDB - Wikipedia

    en.wikipedia.org/wiki/TimescaleDB

    [6] [7] TimescaleDB is a relational database [8] and supports standard SQL queries. Additional SQL functions and table structures provide support for time series data oriented towards storage, performance, and analysis facilities for data-at-scale. [9] One of the key features of TimescaleDB is its performance, which has been compared to ...

  7. Scale analysis (mathematics) - Wikipedia

    en.wikipedia.org/wiki/Scale_analysis_(mathematics)

    Scale analysis anticipates within a factor of order one when done properly, the expensive results produced by exact analyses. Scale analysis rules as follows: Rule1-First step in scale analysis is to define the domain of extent in which we apply scale analysis. Any scale analysis of a flow region that is not uniquely defined is not valid.

  8. Logistic regression - Wikipedia

    en.wikipedia.org/wiki/Logistic_regression

    x m,i (also called independent variables, explanatory variables, predictor variables, features, or attributes), and a binary outcome variable Y i (also known as a dependent variable, response variable, output variable, or class), i.e. it can assume only the two possible values 0 (often meaning "no" or "failure") or 1 (often meaning "yes" or ...

  9. Reverse index - Wikipedia

    en.wikipedia.org/wiki/Reverse_index

    In database management systems, a reverse key index strategy reverses the key value before entering it in the index. [1] E.g., the value 24538 becomes 83542 in the index. Reversing the key value is particularly useful for indexing data such as sequence numbers , where each new key value is greater than the prior value, i.e., values ...