### Opis (description)
The lecture is on **the theory** behind the information integration systems.
**What it is about**
Information integration is the problem of combining data from multiple sources
into one unifying view. There are two different approaches to information
integration: data exchange and data integration. The main goal of data
exchange is to transform data expressed over _source schema_ into a database
over _target schema_ preserving the relationship specified by so-called
_schema mappings_. The main goal of data integration, on the other hand, is to
enable query answering without insisting on the materialization of the target
database. One of possible options is to rewrite queries expressed over a
target schema in such a way that they could be executed over the sources.
**Simple real-world scenarios**
* (data integration) Assume we have data about room reservations in (thousands of) hotels. Possibly each of the hotels stores data in a different format. We want to offer a service for travellers (such as booking.com, expedia etc.) enabling them to compare prices and book rooms. We would like to be able to answer queries without attempting to materialize a single unified view of all data.
* (data exchange) Company A has bought some other company, say company B. The company B stores a lot of data (customers, providers, etc.) in some format that is specific for B. All such data has to be transformed into the format used by A.
**Program**
We will start from an introduction to database theory. In the main part we
show the main theoretical concepts and techniques in the area.
**Motivation**
_Large enterprises spend a great deal of time and money on "information
integration" (...) Frequently cited as the biggest and most expensive
challenge that information-technology shops face, information integration is
thought to consume about 40% of their budget. Market-intelligence firm IDC
estimates that the market for data integration and access software (which
includes the key enabling technology for information integration) was about
$2.5 billion in 2007 and is expected to grow to $3.8 billion in 2012, for an
average annual growth rate of 8.7%._ (Information Integration in the
Enterprise, P.A. Bernstein, L.M. Haas Communications of the ACM 2008,
[link](http://cacm.acm.org/magazines/2008/9/5327-information-integration-in-
the-enterprise/fulltext)).
**Requirements**
Students should have completed at least one of the lectures:
* Formal Languages and Computational Complexity (JFiZO)
* Algorithms and Data Structures (AiSD)
* Databases (Bazy danych)
* Discrete Mathematics (Matematyka dyskretna)
