  In data management, and in particular in data integration, data exchange,
query optimization, and data privacy, the notion of view plays a central role.
In several contexts, such as data integration, data mashups, and data
warehousing, the need arises of designing views starting from a set of known
correspondences between queries over different schemas. In this paper we deal
with the issue of automating such a design process. We call this novel problem
"view synthesis from schema mappings": given a set of schema mappings, each
relating a query over a source schema to a query over a target schema,
automatically synthesize for each source a view over the target schema in such
a way that for each mapping, the query over the source is a rewriting of the
query over the target wrt the synthesized views. We study view synthesis from
schema mappings both in the relational setting, where queries and views are
(unions of) conjunctive queries, and in the semistructured data setting, where
queries and views are (two-way) regular path queries, as well as unions of
conjunctions thereof. We provide techniques and complexity upper bounds for
each of these cases.
