Semantic search in databases

Tomas Drencak

The problem

Search in used cars database

Cca 100k advertisements, all classified:Brand, type

Mileage, Displacement, Year of production, Gasoline/Diesel, Transmission

Equipment:Abs, esr, air condition...

The solution

Search

Faceted search

Semantic search

Fulltext search

Search

Faceted search

Fulltext search

Semantic search

Semantic search seeks to improve search accuracy by understanding searcher intent and the contextual meaning of terms as they appear in the searchable dataspace

The problem

Free form search query:Auto do 5000 eur

Octavia do 100 000 km, max 8000 eur

Octavia klimatizacia tempomat

Mazda 626 1.6 tdi

Context free grammars

S aS aSS bS

Terminal symbol: SNon-terminal symbols: a, b

CFG example #1

aaba

S2aba

S2S2ba

S2S2S3a

S2S2S3S1

S1 aS2 aSS3 bS

CFG example #2

Q Qx | Qx Qx | Qx a Qx | Qx , Qx Qx VYKON | CENA | WORDVYKON od NUM kw | do NUM kw | NUM kwCENA do NUM eurNUM [0-9]+WORD [a-z]+

skoda favorit do 5000 eur a 100 kw

skoda favorit do 5000 eur a 100 kw

Q

WORD

WORD

CENA

VYKON

CFG example #2 SQL query

Q([WORD(skoda),WORD(favorit),CENA(500,