6.User Study Results As query complexity increased, autocorrection tool performs significantly than DM. (For the two easier task, DM was faster.) Users found autocorrection and display of non-answers to be useful for query debugging. Increasing Difficulty
7.Auto-correction When query complexity increases, debugging becomes hard → autocorrection correcting misplaced tuples into answer and non-answer categories System looks at the space of all “tweaks” to the current query tree and recommends query tree
8.Problem Existing query specifications makes it hard to specify quantified queries. VIQING: Visual Interactive QueryING, Olsten et al. (1998) Faceted Search
9.Summary DataPlay: easier trial-and-error specification quantified queries. Nested universal table data model Syntax locality: Toggling of existential and universal quantifiers. “Tweaks” to queries could be done through graphical manipulation of query tree. Lack of non-answers: Query correction via examination and selection of answers and non-answers examples.
10.Data Model nested universal relation=nested data model+ universal relations Benefits: no need for joins or group construction closed world assumption ∴ non answers can be easily computed as (universe - answers) The nested universal relation data model, Levene and Loizou (1994)