# Imieliński-Lipski algebra

**Imieliński-Lipski Algebras**

An Imieliński-Lipski algebras is an extension of relational algebra onto tables with different types of null values.wikipedia

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### Null (SQL)

**NULL NULLs**

An Imieliński-Lipski algebras is an extension of relational algebra onto tables with different types of null values.

The groundbreaking work of T. Imieliński and W. Lipski Jr. (1984) provided a framework in which to evaluate the intended semantics of various proposals to implement missing-value semantics, that is referred to as Imieliński-Lipski Algebras.

### Witold Lipski

**W. LipskiW. Lipski Jr.**

This “Igor” will be missed by SQL and the SQL answer won’t be complete according to completeness requirements specified in Tomasz Imieliński, Witold Lipski, 'Incomplete Information in Relational Databases'.

This collaboration produced a fundamental concept that became later known as Imieliński-Lipski Algebras.

### Tomasz Imieliński

**Tomasz Imielinski ImielińskiT. Imieliński**

Imieliński-Lipski algebras were introduced by Tomasz Imieliński and Witold Lipski Jr. in 'Incomplete Information in Relational Databases'

Imieliński's early work on 'Incomplete Information in Relational Databases' produced a fundamental concept that became later known as Imieliński-Lipski Algebras.

### Relational algebra

**joinJoin (relational algebra)relational logic**

An Imieliński-Lipski algebras is an extension of relational algebra onto tables with different types of null values.

### SQL

**Structured Query LanguageSQL databaseSQL Databases**

For example, it is well known that the 3-valued logic approach to deal with null values, supported treatment of nulls values by SQL is not complete, see Ullman book.

### Jeffrey Ullman

**Jeffrey D. UllmanUllmanJeff Ullman**

For example, it is well known that the 3-valued logic approach to deal with null values, supported treatment of nulls values by SQL is not complete, see Ullman book.