Ky yhi HQi thto ICT.rda'06 Proceedings of ICT.rda'06. Hanoi May.
MQT SO PHEP TOAN DAI SO QUAN HE Md
R O N G T R (CO s d DU* LIEU QUAN HE MOf CHU'A CAC GIA TRI NGON N G C VA U N G DUNG
Some Extended Operators of Fuzzy Relational Database inclu Linguistic Values and Applications
Tr4n Dinh Khang, Phan Anh Phong Tom tSt
Bdi viit de xudt mgt mo hinh cho ca sd dir lieu quan he md dua tren sy kit hgp ngir nghi cua gid Wi ngon ngii v&i trgng sd cua moi bg. Gid tri trgng sd cd the dugc xem Id gid ti chdn ly ciia mdi menh de md. Viec gidi quyit vdn di xdp xi ngir nghia giiia cac gid ti trong mien tri ma dugc llofc hien tren ca sa hdm xdp xi ngii nghTa Sp(.). Bdi viet ding d' xudt mgt phuang phdp loai bg du thira. vd xdy dung mgi sd phep lodn dgi so quan he mi rgng theo xdp xi ngQ nghTa Cdc kit qud Ihu dugc da cho ihdy linh hiru ich cua md hinl ciing nhu cdc phep todn Dgi sd quan he mdi.
Tir khod: ca sa da lieu quan hi ma. xdp xi ngu nghTa. dgi sd gia lu Abstract
This paper proposes a model of fiazy relational database based on meaning combination of linguistic values and the weighted degree of a tuple. The weighted degree can be considered as a truth value of fiizzy propositions. The problem of meaning approximation of fuzzy values in fiizzy domains can be solved by using the meaning approximate function SP(.) of hedge algebras. The paper also proposes a method for elimination of redundant tuples, and after that, defines some extended operators of fuzzy relational database. The results show the advantage of our model by processing some query demands.
Keywords: fiazy relational database, meaning approximation, hedge algebra
1. MOf DAU mpt van dk niy sinh ty nhien va tit yeu Md hinh di? lifu quan hf dugc E. Codd dl ^^P^' ^f\ "^X' '^P ""j'l" "^^^g ^'^P ^ xuit nhihig nim 70' da danh diu mpt m6c g^' ^"y^L^*" ^^ ?"y- J\^, '^ ''v.ng ly tl phit triin quan trpng vl co sd ly thuylt cung J ? """[-• ^ mo rpng CSDL quan hf ti
u iL- - ' J ' ' u« ' J - thong da dupe dong dao cac tic eia Guar nhu kha nang ung dung cua cae h? co so du ^ ^ » ^ "^^ gia quar lifu (CSDL), cung vdi sy ra ddi cac hf quin [V rU{- - IJ- ^V ^ "^ ^'''^'' tri CSDL thuong mai DB2, Fox,... vi sau niy » ^ ^ 5 " " *?^\"?'''c'i!;r "*'""• "^^^ '^^}
li M. Access, SQL Server, Oracle, ... Tuy ^ J V ^ * ^ ^^^^f^^ ^"^".^e kinh die nhifn, sau dd Codd da nhin thiy dilm h^n ehl ^° ^ i "^"^ ^ \ ^.^^ ^^y ^«" <=hua thdn;
cua md hinh trong viec bilu diln dQ lifu "!*'• ^ "'^'^ l''^ ''^'' Y'?^ ""^^ '^^E khdng lu- J- J ' » >t» ' - imn - >*- • dung I91 o cac truy van mo. mi cdn chn r khong day du, nen den nam 1979 ong da mo , f _ , . , , / . , ... ' " " ^ " " F
» • u' u u- 'A- I - II \ / - luu tru va xu ly cac du leu md rpng mo hinh quan hp voi du lipu null. Vipe •' ^ '""•
dua vio gii trj null trong cac hf CSDL quan , Trong thi gidi thyc da so dir lifu cd d hf kinh diln da phin nao khic phyc dugc sy ^ 1 " mpt thdi dilm nao dd la khdng chinh) khdng diy dii thdng tin nhung each lim nay khdng rd ring hay cdn gpi li dir lifu md.
cdn rit han ehl vl ngu- nghTa. Nhu viy, xir ly hpc ngiy cang phit triin thi yeu ciu cua thdng tin khdng chinh xic, khdng rd ring li h? thong thdng tin ngiy cang phai md phe
^^hm
i thto ICT.rda'06 Proceedings of ICT.rda'06. Hanoi May. 20-21.2006thi gidi thyc mpt each trung thyc hon. Tir dd f^ sinh vin dk giii quylt bii toin co dir lifu khdng chi li nhOmg con s6 ma cdn chua cic gii tri ng^n ngQ'. Sy xuit hifn ciia Idp cic bai toin niy cd thi do nhirng ly do sau: Mdt la, cic bii toin mi myc tieu danh gia khong phii bing cic con so. Ching ban, ''Chdt lugng ddo tgo eia mgt trudng dgi hpc". Hai li, cac bai toan mi vifc dinh gii bing so la khd khan va khdng thuin Igi. Khi dd, con ngudi thudng dung cic gii trj ngdn ngQ dl bilu dien. Va ba la, sy xuit hifn thudng xuyen, ty nhien cua cic gii trj ngdn ngu- trong cic yeu ciu tim kiim thdng tin ciia con ngudi. Vi du, "Hay cho biit khd chinh xdc nhirng mdy tinh trong mgng LAN co hi4u ndng cao ".
Vdi nhu-ng phin tich tren, cho thay nhu ciu nghien ciiru CSDL quan he md chiira cac gii trj ngon ngir la xac dang va phu hgp.
Hudng tiep can nay ciing da dugc mpt so tac gia quan tim [1] [2] [6] [9]. Trong [6] da dua ra mpt mo hinh toan hpc dya tren quan he thu ty bp phan (Quasi-Order Relation) cimg vdi ly thuyet udc lugng tinh hudng va tip hgp (evaluation problems and sets) de gan eac gia trj cho cac thupc tinh cd mien trj la ngdn ngCr nhung no vin chua cd nhu-ng nghien ciru cu the ve thao tic dii' lifu md. Trong [1] da de nghj mpt md hinh cd the xiir ly vdi cac gia trj ngdn ngir dya tren tu tudng ciia Petry va Bukles [7]. Tuy nhien, each tiep cin nay gap kho khan trong vifc xiy dyng cic quan hf tuong ty tren mdi mien thupc tinh.
Bai viet niy se xem xet CSDL quan hf md chiia cac gii trj ngdn ngu- bing each kit hpp vifc xap xi ngir nghTa ngdn ngii vdi gia trj trpng so ^, tip cic gii trj ngdn ngQ' ciia mdt thupc tinh dupe bilu diln trong mot ciu true d^i so gia tiir [11]. Vifc xac djnh dp xip xi ngir nghTa giiia cic gii trj dupe xiy dyng dya tren ham djnh lupng ngii nghTa trong [3], con ^ dupe xem la gia trj chin ly trong mdi mfnh de md. Bii vilt dugc td chirc thanh 5 phan: sau phin md diu, phin 2 dua ra md hinh CSDL quan hf md chira cic gii trj ngdn ngii' vi xiy dyng cic khii nifm mdi: khii nifm xip xi ngii nghTa giOra cic gii trj ngdn ngii; xip xi ngiir nghTa giu'a mpt so va mpt gii trj ngdn
ngir,... Tir dd, xiy dyng ham xip xi ngii' nghTa ciia hai bp va phuong phip loai bp du thira trong quan hf md. Trong phin 3 trinh biy mpi sd phep toan dai sd quan hf md rpng. Cic irng dung d phan 4 cho thiy tinh hiiu ich ciia mc hinh cOng nhu cac phep toin dai so quan he mdi. Phin cuoi cung la mpt so gpi md cho cac nghien cuu tilp theo.
2. MO HINH CO Sd DC LIEU Md CHU'A CAC GIA TRI NGON N G C
Hifn nay, da sd cic nghien ciru vl CSDL quan he md deu la sy md rpng ciia md hinh CSDL quan hf truyen thong, do viy, diiu cin thiit phai giai quylt la sy khdng chinh xac trong cac gia trj ciia moi thupc tinh, va sy khong chinh xac trong vifc ket hpp cac gia trj ciia cic thupc tinh khac nhau. Vifc bieu dien dir lifu bing cac gia trj ngon ngii' da phan nao giai quylt dugc van de thir nhat. Con de khic phuc van dl thu hai, chiing ta co the su dyng gia trj thanh vien (dp thupc) cho mdi bp. Tire la, bd sung them mpt thupc tinh die bift, p., cho mdi quan hf, miln trj ciia thupc tinh nay CO thi la cae so thyc trong doan [0,1 ] hoic cac gia trj chin ly ngon ngir. Tuy nhien, cac quan hf gin vdi trpng so cd the dupe hiiu theo nhilu each khac nhau, nd phy thupc vao y nghTa ciia trpng so. Trong [7] da chi ra mpt so y nghTa ciia p. nhu sau:
• Trpng so n thi hifn dp thupc ciia mdi bp trong quan hf. Diy cung la each tilp cin trong [2].
• Trpng so p thi hifn dp do khi nang cua vifc kit hpp cic gii trj trong mdi bp, cac gia trj nay cd thi rd hoac md hoac gii trj ngon ngii'.
• Trpng sd \i thi hifn dp thda cua cic khai nifm md dupe liru trii trong moi bp.
Trong bai viet nay, chiing ta nhin nhin gia trj ciia thupc tinh p, p(t)^ nhu la gii tq chin ly ciia mfnh dl md (mdi bp). Hay noi each khac p(t) thi hifn mire dp khing djnh cua thong tin luu trii trong bp dd. Vi dy vdi bp
"Nam, Rat tre, Gidi, 0.95" trong quan hf SinhVien(Ten, Tuoi, HocLuc, p) se dupe
Ky yiu HQi thto ICT.rda'06 Proceedings of ICT.rda'06. Hanoi May.:
hiiu nhu mpt mfnh dl md: Sinh vien Nam rat trf cd hpc lye gidi li 0.9S.
Gii su W=(A|, A2, ..., A„, ^i} la tap cac thupc tinh. Ki hieu dom(Aj) la cac mien trj tuong irng ciia cac thupc tinh Aj, i = 1 , 2 , . . . , n.
D I tif n lgi ta chi xet cac dom(Ai) hoic la cic gii trj rd hoac li cac gii trj ngdn ngir hoic li miln kit hgp giira cac gii trj so vdi gia trj ngdn ngir. Cic gia trj ngdn ngir ciia mdt thupc tinh dugc bilu dien bing mpt cau true dai so gia tir. Miln trj cua ^, dom(^), li doan [0,1]
hoic cic gia trj chin ly ngdn ngir.
Dinh nghia 2.1. (Quan hf md)
Mpt quan hf md fr (Fuzzy Relation) li mpt tip con cua tip tich Dk-ckc dom(Al) x dom(A2) X...X dom(Ap) x dom(Ap+i) x ...x dom(A„) X dom(^), trong dd, Ai,..., Ap l i cic thupc tinh cd mien tri rd; Ap+i, ..., A„ l i cic thupc tinh cd miln trj khdng rd nhu da gidi ban d tren.
Vi du: Qaan hf Sinhvien(Ten, Tuoi, HocLuc, p.) li mpt quan hf md. Thupc tinh Ten cd miln trj rd; cdn Tuoi, HocLuc li cac thupc tinh cd miln tri khdng rd.
Bang 1. Vi dy ve quan hf mor chiira cac gia trf ngon ngiir
Ten Nam
Hai Luong
Tuoi RitUe Tuong d6i tre
25
HocLuc Gidi 8.50 Trung binh
^ 0.95 1.00 0.70 Djnh nghTa 2.2. (Bp dir lifu)
Mdt bp di^ lifu trong quan hf md fr cd d?ng (t,^fi(t)), 0<Hft(t)<l. Trong dd, ter v i r c dom(A|) X...X dom(A„).
C^uan hf fr cd thi dugc viet l^i nhu sau: fr
={(t,lifr(t)):Mft(t)6(0.1]Ater}.
Vifc so sinh giira cac gii tri dQ lifu trong CSDL la mdt yeu ciu thudng xuyen, doi vdi CSDL md chira cic gii trj ngdn ngCl, vin dl nay dupe tiep cin theo hudng xap xi ngir nghTa. Can so sanh dugc hai gii trj ngon ngir, hoac giira gii trj sd va gia trj ngdn ngu*. Sau
diy li cic him do xap xi ngii' nghTa gia trj.
Hdm do xdp xi ngir nghia giura hi ngon ngit
Theo [11] thi tap gia tri X ciia , ngdn ngir cd thi dugc bilu thj nhu m gia tii AX=(X, G, H, <), trong dd, G L phin tiir sinh, H la tap cac gia tiir cdn q tren cac tir li quan he thiir ty dugc "ca tir ngir nghTa ty nhien. Trong bai nay dai so gia tiir doi xiimg, tire la mdi trong AX chi (id mpt phin tir doi nghjc
Gii sir f|, f2 e X. Ham do xip nghTa (Semantic Proximity) ciia f| v hifu li Sp(f|, f2) dugc xac djnh:
Sp(f,.f2)= 1- iv(f,)-v(f2)l
d diy, v: X-»[0, 1] la ham djnh lugi nghTa ngdn ngir trong [3].
Nhu viy, vdi f|, fz € X ta ludn cd:
0 < Sp(f,, f2) < 1 (Chuan Sp(f,, f,) = 1 (Phan X.
Sp(f,, f2) = Sp(f2, f,) (Dii xir Theo [4], thi Sp(.) cd thi dugc xi mpt quan hf giong nhau (resemb relation) tren X.
Ham do xdp xi ngir nghia giira mpt gid va mpt gid trf ngon ngir
Vdi dai so gia tii AX thi sd lugng ca trj ngdn ngir cd cimg dp dai ciia chuoi g tic dpng vao phin tiir sinh cd the xac dupe theo lye lupng cua tip gia tir. Do chiing ta cd thi chia khdng gian nIn (mil CO sd) ciia biln ngdn ngir thanh cac khc cho timg gii trj ngdn ngir, theo quan hf th tren AX.
Khi dd, vifc so sanh ngir nghTa giira gia trj so va mpt gia trj ngdn ngir cd thi t hifn nhu sau:
- Chia mien trj co sd thanh cac kho;
(cd the khdng diu nhau)
- Gan mdi khoang tuong irng vdi mdt trj ngdn ngir trong AX theo thu ty tu nhidn
KjllS ,fa Wt thto ICT.rda'06 Proceedings of ICT.rda'06. Hanoi May. 20-21,2006
. Sii dyng him Sp dl xic djnh xip xi ngii nghia giu:a chiing
Him do xdp xi ngSr nghia giira hai gid tri trong mien ro
x,, X2 e dom(Ai) vdi i= 1, 2, ..., p. Ky hifu EO(xi, X2) la him do xip xi ngir nghTa giaa chung.
nlu x, = X2thi EQ(x,, X2) = 1, ngugc i?ii EQ(xi,X2) = 0
Tren co sd cac ham do xip xi ngir nghTa gii^a cic gia trj ngdn ngir hoac vdi gia trj sd, chiing ta cd the djnh nghTa sy xap xi ve ngir nghTa cOa hai bp trong quan hf md.
Djnh nghia 2.3. (Ham do xap xi ngii' nghTa cua hai bd trong quan hf r)
Gii sir: (ti,^f^(ti))efr, (tj,^ifr(tj))efr, trong do ti=(Xii, Xi2, ..., Xi„)€r va tj= (Xji, Xj2, ..., Xj„)Gr; rcdom(Ai) x ... x dom(An).
Ki hifu SP(ti,tj) la ham do xap xi ngir nghTa cua hai bp tj, tj va dugc xac djnh nhu sau:
SP(t|, tj) = min{EQ(Xjk, XjO, Sp(Xih, Xjh)}
vdi, Xik, Xjk G dom(A|(), k = 1, 2,..., p; xih, Xjh € dom(Ah), h = p+1,..., n.
Djnh nghTa 2.4. (Sy giong nhau ciia hai bp trong quan hf r)
r c dom(Ai) x...x dom(An). a € (0,1]. tj, tj 6 r dupe gpi la gidng nhau theo miic-a khi va chi khi SP(ti, tj) > a. Ki hifu sy giong nhau nay la ti«atj.
NIU SP(tj,tj)< a thi ta gpi t; va tj la phan bift nhau d mirc-a, va ki hieu tj^^otj.
Sy giong nhau ciia hai bp theo miic-a la CO sd dl loai nhihig bp du thira ra khdi CSDL Phep logi bg du thira trong CSDL quan hi ma
Cho quan hf md fr xac djnh tren W, ae[0,l]. Phep lo^i bp du thira trong fr theo mirc-a, ki hifu la Da(fr) vi dugc thyc hien nhu sau:
Nlu hai bp (ti,^ft(ti))efr, (tj,Mtj))€fr, i ^ j , ma SP(ti,tj) > a, khi dd, ta lo?i bp c6 gii tri
trpng so pft nhd hon. Mpt vin dl dit ra, trong trudng hpp cic Pfr bang nhau thi chiing ta xoa bp nao trong cac bp nay? Cac tilp can trudc day, [2] [9] diu tuy y giii lai mpt bp dai dier trong cac bp dd. Do viy, kit qui ciia vifc loai bp du thira trong CSDL quan hf md la khdng nhit quan! Dk khac phuc diiu niy, chiing ta cd the thay thi cic bp dd bdi mdt bp khic ciing ngir nghTa. Bp mdi dupe tao ra tiir cic b^
cu theo quy tic sau.
Doi vdi cic miln gii trj rd thi tit nhien
•chiing ta giir nguyen cac gii trj, ngupe lai (cic thudc tinh co mien trj khong rd), thi
+ Neu ci hai la cac gii trj ngdn ngir thi ta giiir gia trj cd djnh lupng ngii' nghTa Idn ban.
+ Con l?i, thi ta giii' gia trj sd trong be mdi.
Tren co sd cae khai niem dupe djnh nghTa trong phan nay da cho phep chung ta co the xay dyng eac quan hf md chiira gia trj ngor ngu" va so sanh cac bp cua no. Van de dat ra tiep theo la md rpng cac phep toan dai so quan hf dl xir ly dupe cae quan hf md nay.
3. MOT S6 PHEP TOAN DAI S6 QUAN HE Md R O N G TREN CO Sd DU* LIfU M b CHU'A CAC GIA TRI NGON N G C Dya tren sy giong nhau giu'a 2 bp trong quan hf md, chiing ta co the djnh nghTa dupe cac phep toan quan hf theo mire a. Cho quar he fr,, fr2 xac djnh tren R(W), a G [0,1], ta cd
Phep hgp mirc-a (Uc) fr,u„fr2 = D„(fr,ufr2)
trong do, fr|Ufr2 la phep hpp cua hai quan hf mdnhutrong[4].
Phep giao miirc-a (nj frl Oa fr2=
{(ti,^f^l(ti)) I (ti,Mfri(ti))efri A
3 (tj,Pfr2(tj))efr2 ASP(Uj)^a A
PfM(t,)^Mtj))
V (tj,Pfr2(tj)) I (ti,Mfr2(tj))efr2 A 3(t„Pfr,(ti))Gfr, ASP(ti,tj)>a A
(^f^2(tJ)^^frl(t,))}
Ky y^u HQi thto ICT.rda'06 Proceedings of ICT.rda'06. Hanoi May. 20-
Phf p trii miirc-a (-0)
fr, -a fr2 = { ( t i , H f t l ( t i ) ) € f r , I V
(tj,Mtj))efr2
ASP(ti,tj)<a}
Phep chpn miic-a
Trong CSDL quan hf md chira cac gii trj ngdn ngii', gia trj trpng so p vi dp xap xi ngii' nghTa giira cic gii trj li co sd cho vifc xiy dyng phep chpn md vi cic phep toin quan hf khac. Dk hiiu siu hon vl phep chpn md mirc- a chung ta xet cac bilu thuc dieu kifn chpn thudng gip.
Gii sur F li diiu kifn chpn, A; li cac thupc tinh, dj GX, a G[0,1]. F cd the cd cic d?ing:
(1). F = (Ai, di, a), nghTa li chpn ra nhung bp mi gii trj t?ii thupc tinh A. thoi dj d mijc-a (2). F = NOT(Ai, di, a), nghTa la, chpn ra nhiing bp ma gii trj tai thupc tinh A, khdng thda d[ d mirc-a
(3). F la hpi (AND) cua cic bilu thirc logic dang (1) (thoi) vi (2) (khdng thoa).
(4). F li tuyln (OR) ciia cac bilu thiire logic d^ng (1) (thoa) va (2) (khdng thoi).
Vdi die trung ciia md hinh nfn chung ta cd thi djnh nghia ph6p chpn theo murc-a theo hai mure: Chpn a-kfaing djnh (certain) va chpn a-cd thi (maybe).
Ki hifu phep chpn khing djnh vi phep chpn cd thi theo diiu kifn F ciia quan hf fr
l i n l u p t l i Ocertain-Kfr). OMaybe-Kfr)- B i l u d i l n
cy thi ciia cic phep chpn niy theo 4 d^ng tren ciia F se li:
(l).F = (Ai,di,a)
- CTcert.in-F(fr) = {(t,lift(t)) e fr : t [ A i ] « a d i A
lifr(t)>a}
- awaybc-Kfr) = {(t,^fr(t) A S P ( t [ A i ] , d i ) ) G
fr:t[A,]«„di}
(2).F = NOT(Ai,di,a)
- CTcenain-Kfr) = {(t.^fr(t)) G fr : t [ A i ] ?tadi A
^ft(t) ^ a }
- OMaybe-Kfr) = {(t,^fr(t) A S P ( t [ A
fr: t[Ai]^„di}
(3). F = P AND Q
- tJcertain-Kfr) - <JCertaiii-p(fr) ^^ CTcena - OMaybe-F(fr) - CrMaybe-p(fr) ' ^ ^Maybc
trong dd, a = minfap, OQ} vdi ap lin luot la miirc a trong bilu thiire chp Q.
(4). F = P OR Q
- OCertain-Kfr) - CrCfitain-p(fr) ' ^ a Ocertain^
- ^Maybe-Kfr) = <JMaybe-p(fr) ^a CrMaybe-(
trong do, a = max{ap, OQ} vdi ap lin lugt la muc a trong bilu thiire chpn Q.
Phep chieu miic-a
Cho fr la mdt quan hf md tren W.
W. Ki hifu phep chieu muc-a ciia fr tre:
thupc tinh A la: na,A(fr). Khi dd, bieu hinh thuc ciia phep chieu miirc-a tren thupc tinh A nhu sau:
n„. A(fr) s Da{t([A], Mt)) : (t, Hfr(t fr}
trong dd, t[A] = (t[B,], t[B2],..., t[B„]
t[Bi] la gia trj cua bd (t,^fr(t)) tai thupc tinl
Phep ket noi tu nhien mirc-a
Cho frl va fr2 la cac quan hf md xac djnh t W, va W2, W, n W2 ?t 0 . Kit noi md cua va fr2 la mpt quan hf md, ki hifu la friViej bao gom cac bp trong fr, x frj sao cho tha phin thiir / cua quan he fr, thoi man phep vdi thanh phin thiiry ciia quan hf fr2.
Nlu bilu thiire kit ndi iGj la t[A]«at'[>
(t,lifri(t))Gfri, (t',Hfri(t'))Gfr2 vi trong quan kit qui vdi mdi cap thupc tinh giong nhau c giir lai mpt, thi phep kit ndi nay dugc gpi phep kit ndi ty nhien muc-a.
Tuy thupc vao tinh chit kit ndi, ta cd the c hai loai kit noi ty nhien miirc-a: kit noi i nhien mgnh mirc-a. ki hieu la fri*sirong.„fr2 v ket noi tu nhien yeu muc-a, ki hieu la fr,*^^^
afr2. Bieu dien hinh thuc ciia chiing la:
1 n
^jhW thto ICT.rda'06 Proceedings of ICT.rda'06. Hanoi May. 20-21,2006
• fr = HI slrong-a " 2
{(t.Mft(t)): 3 ti,Hfr,(ti)) G fr, A (tj,^M(tj)) e fr2 A (ti[A]«„tj[A]) A (^fr,(ti) ^ ) A (^ft2(tj) ^a)}
trong dd, fr xic djnh tren W, u W2 va |ifr(t) = inin(^fri(ti),li«r2(tj))
• fr = frl *weakKJ fra -
{(t, pfr(t)): 3 (ti,^ft,(ti))G fr, A (tj,Mtj))efr2Ati[A]«„tj[A]}
trong do, fr xac djnh tren W1UW2 va fi^t) = min(pfr,(ti),Mtj),SP(ti[A],tj[A])).
Cac phep toan fren cho phep thyc hifn dupe cac thao tic xiir ly dii lifu, gdm c i cip nhit vi truy vin trSn quan hf md. Ngoii ra, chiing ta cung cd the khai thic cac die trung xiir ly ngon ngii ciia cac phep toan nay trong mpt sd ung dyng dupe trinh bay d phin tiep theo.
4. iTNG DVNG
4.1. Ho trg xiir ly cac truy van chira gia tri ngon ngir
Dgng 1: Dua ra cic bp cd thupc tinh Ai thoa/ khong thoa d, a mire dp ai. d|, ai e X, vdi X la miln trj ngdn ngii' dupe bieu dien bdi cau triic dai so gia tir. 6 day, tuy thupc theo tinh chat ciia cac truy van mi cic phep chpn
Clcenain-F(fr), aMaybe-F(fr) SC d u p C Sir d y n g .
Dgng 2: Td hgp logic AND hoic OR cua d^ng 1, chiing ta se ket hgp phep chpn md vdi phep hpp mirc-a hoic phep giao mirc-a de tra Idi truy van niy.
4.2. Ho trg xir ly cac truy van chira cac lugng tir md "tat ca" , "hau het"
Vi dy, xet truy vin "dua ra tdt cd cic sinh vien hpc gidi^\ Khai nifm tdt cd gioi se dupe hiiu nhu thi nao? D^i so gia tir AX ma chiing ta dang xet la dai sd gia tu ddi xiimg co hai phan tiir sinh, trong trudng hgp niy li: gioi vi yeu. Theo djnh nghTa tinh md ciia khai nifm md trong [3] thi dp md ciia gioi chinh li kich cd ciia tip \\{gidi) v i dd chinh li tip "/d/ cd gidr. Nhu viy, dp xip xi ngii nghTa giiira
"gioi" vi "tdt cd gioi" sg dupe xic djnh. Ki
hifu muc xip xi dd la a,,, thi a,,, dupe tinh theo cong thirc sau: Oan = l-|v(gioi)-w|
Ap dung phep chpn md vdi F = (HocLuc, gioi, cXa,i) ta CO ket qui eiia truy van.
Y tudng dl xiir ly vdi lupng tir hdu hit ciing tuong ty nhu tren. Tiic li, cin phai xic djnh dupe muc dp xip xi ngft nghTa.Tuy nhien, vi lugng tir nay phy thupc rat nhilu vio ngudi dimg nen chiing ta chi cd thi xic djnh mire xip xi trong mpt khoing nao do. Gii sir xet truy vin "dua ra hdu hit cac sinh vien hpc gidr. Theo ngii nghTa ty nhien thi lupng tir tdt cd manh hon lupng tir hdu hit. Nhu viy, thi xip xi ngir nghTa giira hdu hit gioi va gioi la o^imost phii thda bit ding thiire sau:
1 ^ahnosl > Call
Can Cli vao khoing gidi ban nay va a.,, ta CO the dua ra ciu tra Idi cho truy vin tren.
4.3. Ho trg viec ket nhap cac y kien Gia sir cho quan hf
KetQuaHocTap-fr(Ten, Lop, HocLuc, p) the hifn sy dinh gii vl hpc lye cua sinh vien tir eac giao vien khac nhau (bing 2).
Bang 2. Ket qua hpc tap ciia sinh vien theo danh gii tiir giao vien Xuan va Ha Ten
An Long
An Long
Lop K45Tin K45Toan
K45Tin K45Toan
Giao Vien Xuan H?
H?
Xuan
Hoc Luc Rat gioi
9.50 Co thi rat gioi Gidi
H 1.00 0.90 0.70 0.85 v i n dl dat ra li cho bilt kit qud hgc tgp chung ciia cac sinh vien. D I tra Idi ciu hdi nay chiing ta cin thong nhit khai nifm "Ape lycc chung". 6 diy, chiing ta dimg phuong phap xip xi ngir nghTa dl tri Idi truy vin nay.
Tire la, chi ra mpt miirc xip xi ngOr nghTa ttagg nao do giira cac gii trj. Khi dd, kit qui cua truy vin s6 dupe xic djnh bdi phep chieu md tren quan hf KetQuaHocTap-fr vdi t|p thupc tinh A={Ten, Lop, HocLuc)} vi a=a,gg.
Ky ylu HQi thto ICT.rda'06 Proceedings of ICT.rda'06. Hanoi May.
Gii sir miirc xip xi ngii' nghTa aagg=0.85 thi kit qui hgc tgp chung ciia cac sinh vien se la kit qui ciia phep chieu no.g5^(KetQuaHocTap-fr) va dugc thi hifn d bang 3.
Bang 3. Ket qua hpc tap chung ciia c i c sinh viln
Ten An Long
Lop K45Tin K45Toin
HocLuc Rit gidi 9.50
11
1.00 0.90 5. KtT LUAN
Tren day la mpt sd phep toin d^i so quan hf md rpng theo tilp cin xap xi ngii nghTa de xii ly quan hf md chira cic gii trj ngdn ngii.
Cach hiiu ve y nghTa cua trpng so |i nhu li gia trj chin ly ciia mfnh dk md, cimg vdi cic phep toan nay da t^o sy thuin Ipi cho cic truy van chua gii trj ngdn ngii trong CSDL quan hf md, cho phep xem xet cac die trung v l ngir nghTa ciia cic gii trj ngdn ngii' trong xiir ly dii lifu ngdn ngii. Mpt so gpi md cho cic nghien ciru tilp theo cd thi li: tiep tyc xem
\6t cic truy vin md chira cic gii trj ngdn ngii ciing vdi lupng tur md, v i nghifn ciiru cic phy thupc dir lifu md cung nhu iirng dyng ciia nd.
Tii lifu tham khao
[1] Hi cim Ha, Mft cich tilp cin md rfng co sd dd lifu quan hf vdi thdng tin khdng day dii, Luin in tiln sT, D^i hpc BKHN, 2001.
[2] Truong Dure Hiing, Mft s6 vin dl vl co sd dfi lifu vdi thdng tin khdng diy dii va lip luin xip xi trong xiir Vf ciu hdi, Luin in Phd tiln sT, Dfii hpc BKHN, 1996.
[3] Nguyin Cit HI, Trin Dinh Khang, Trin Thii Son, L6 Xuan Vift, "Fuzziness Measure, Quandfleld Semantic Mapping and Interpolatic Method of Approximate Reasoning in Medical Expert Systems", T^ip chi Tin hpc va Diiu khiln hpc T.18, S.3 (2002), 237-252.
[4] Chin-Teng-Lin and George Lee C. S., Neural Fuzzy Systems, Prentice-Hall Inter., Inc. 1995.
[5] Kacprzyk J., Ziolkowski A., "Database Queries with Fuzzy Linguistic Quantifiers", IEEE Transactions on Syst., Man, and Cyb. Vol SMC-I6n»3, 1986.
[6] Kerre E., De Cooman G. and et al "
Linguistic Terms in Database Proceedings IPMU'96, Sixth Int Granada, Spain, Vol! Ill, 1996, pp. 1 [7] Petry E. and Bosc P., Fuzzy
Principles and Applications, Kluwer Publishers, 1996.
[8] Shenoi S, Melton A. "Proximity Re the Fuzzy Relational Databases". F Syst 1989;3I(3):285-296.
19] Zhang W. Clement Yu, Bryan Res Hiroshi Nakajima '^Context Dt Interpretations for Linguistic T Fuzzy Relational Databases". In IE Conf. on Data Engine'ering, pp. 1 1995.
[10] Bhattacharjee Tapan K., Mazumdar i
"Axiomatisation of Fuzzy Mul Dependencies in a Fuzzy Relation;
Model", Fuzzy sets and systems 96, 352,1998.
[II] Wechler W., Nguyen Cat Ho, Algebra: An Algebraic Approach to Sti of Sets of Linguistic Systems", Fuzzy s systems, 1990.
Ve cac tac gia:
PGS.TS. Trin i Khang, tdt nghifp Dai nganh Toan diiu khili ky thuit tinh toin t£ii Trt Dfii hpc Tdng hpp Ky t Dresden, CHLB Due, bii luin in tiln si t^ii Tru D^i hpc Bich Khoa Ha I PGS. Trin Dinh Khang 1 dang cdng tac tai Ki Cdng nghf thdng Trudng Dai hoc Bich Kl Ha Ndi.
vin dl quan tam chinh: Logic tinh toan.
Email: [email protected]
Th^c sy Phan Anh Phong, bio vf luan van di?c sy chuyen nganh cdng nghf thdng tin t^i Trudng Dai hpe Bich khoa Ha Nfi, nSm 2004, hifn nay dang lam vifc t^ii Khoa Cdng nghf thdng tin, Trudng Dai hpc Vinh.
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