Document retrieval method and system and computer readable storage medium

(54) DOCUMENT RETRIEVAL METHOD AND SYSTEM AND COMPUTER READABLE STORAGE MEDIUM

(75) Inventors: Natsuko Sugaya, Kawasaki (JP);

Katsumi Tada, Kawasaki (JP);
Tadataka Matsubayashi, Yokohama
(JP); Akihiko Yamaguchi, Yokohama
(JP); Yasuhiko Inaba, Yokohama (JP);
Yousuke Ushirqji, Osaka (JP)

(73) Assignee: Hitachi, Ltd., Tokyo (JP)

( * ) Notice: Subject to any disclaimer, the term ol this patent is extended or adjusted under 35 U.S.C. 154(b) by 158 days.

(21) Appl. No.: 09/645,561

(22) Filed: Aug. 24, 2000

(30) Foreign Application Priority Data

May 9, 2000 (JP) 2000-142232

(51) Int. CI.7 G06F 17/30

(52) U.S. CI 707/6; 707/5

(58) Field of Search 707/1, 2, 3, 4,

707/5, 6, 101, 102; 345/589

(56) References Cited

U.S. PATENT DOCUMENTS

5,926,808 A * 7/1999 Evans et al 707/1

6,026,409 A * 2/2000 Blumenthal 345/589

6,289,353 Bl * 9/2001 Hazlehurst et al 707/101

A document retrieval system is provided which has a document display interlace which is easy to recognize the important portions even il a document retrieved by using a query expression designated by a document or a long sentence is displayed. When a text is registered, predetermined character strings and location information which are extracted from the text are stored in a location information file. A weight ol each character string is calculated by a predetermined method and is stored in a weight file. In retrieving a document, predetermined character strings are extracted from a designated query expression. A similarity is calculated between the query expression and texts in the database by using the location information and the weights acquired from the location file and the weight file. In displaying the document, character strings having the high weights are extracted from the character strings used for the retrieval. Then, the display format ol a portion which contains the extracted character strings is changed to display the text.

12 Claims, 15 Drawing Sheets

DOCUMENT 1: CONTAINS factors, information, human and retrieval

V1 = (1,1,0,1,0,1,0)

DOCUMENT 2: CONTAINS factors, help, human and systems

V2=(1,0,1,1,0,0,1)

DOCUMENT 3: CONTAINS factors, operation and systems

V3=(1,0,0,0,1,0,1)

SIMPLE RANKING
00=0,1,0,1,0,1,1)
V1 = (1,1,0,1,0,1,1)

V1-Q0=(1,1,0,1,0,1,0)=4

Qo=o,i,o,i,o,i,i)

V2=0,0,1,1,0,0,1)
V2-Q0=(1,0,0,1,0,0,1)=3

00=0,1,0,1,0,1,1)
V3=0,0,0,0,1,0,1)
V3-Q0=(1,0,0,0,0,0,1)=2

RANKING USING WEIGHTS

00=0,1,0,1,0,1,1)
V1 = (2,3,0,5,0,3,0)
V1-Q0=(2,3,0,5,0,3,0) = 13

00=0,1,0,1,0,1,1)
V2= (2,0,4,5,0,0,1)
V2-Q0=(2,0,0,5,0,0,1)=8

00=0,1,0,1,0,1,1)
V3= (2,0,0,0,2,0,1)
V3-Q0=(2,0,0,0,0,0,1)=3