T^p chi Tin hgc v& DiSu khiSn bqc, T 27, S.2 (2011), 131-141
CHUAIM HOA CAC L 6 P DOI Tl/ONG TRONG Ll/CJC o d Cd Sd DUf LIEU Hl/dNG DOI TLTONG M6
DOAN VAN BAN' , H 6 c.kM HA2 . \ u Dire QUANC''
^ Vien Cdng ngh$ Thdng tm, Vien Khoa hpc vu Cong ngh^ Vi$t Nam
^ Triidng Dg.i hpc Sil php.m Hd npi
^ Triidng Dai hpc Quang Nam
Tom t a t . Bai bdo vp nghien cihi phy thudc md giita cdc tliuOc tinh trong mot ldp ddi tUOng. Tuorig tu nhu trong co sd dC li?u quan he md ro, da dua ra cdc dang ehuan doi tUdng md (IFONF. 2F()NF.
3F0NF) va cac thu^t todn chudn hoa ldp \-f cdc dgng chuin trong co sd diJ heu hudng ddi titdng md.
Abstract. In this paper, we study fuzzy dependencies between attributes in an object class. Similarly in the fuzzv (clear) relational database, we present the fuzzy object normal forms (IFONF, 2F0NF, 3F0NF) and class normalizing algorithms for normal forms in fuzzy object-oriented c
1. Gl6l THIEU
Trong nhiing nam gdn dd\-. viec nghien cu\i, ling dung cd sd dii lieu hudng ddi tUdng (CSDL HDT) md d^ giai qu>et nhiing han chg cua cO sd dii lieu quan he/hudng ddi tUdng ro trong
\iec xd ly va liTu trii cac thong tin khong elide chdn, khong ddy du trd thdnh mpt chu de nghign ciiu quan trpng trong mot s6 linh vuc cua khoa hpc mdy tinh [5]. Tiep can hudng ddi tUdng rad trong vigc thiet ke cdc he thdng phdn m^m da nhan dugc mpt sU chu y ddng kg, dat biet la trong linh vuc cd sd dii heu. Ciing giong nhu trong cd sd dS Ufu kinh diSii, trong CO sd dii lieu md cd fhi cd du thiia dii lieu va cac di thudng khi cdp nhdt nSu nhu cdc lUOc d6 fO sd dd: lieu khdng dUdc thiet kl mot each thich hop [2, 6, 10]. Thong thudng, cac phu thupc dii lieu Id tri thdc ngii nghia ve the gidi thuc va dUOc xem nhu cac rang buoc todn ven doi vdi vifc thiet ke cd sd du: lieu.
Dua tren cdch thiic tinh dp tuong dUdng ngfl nghia cua hai dii lieu md, dua ra cdc dmh aghia vg phu thu6c hdm md trgn ldp ddi tUdng md. Ngoai ra, cdn gidi thieu ba dang chudn ifloi tUdng md IFONF, 2F0NF, 3F0NF va cdc thudt todn chudn hda ldp vg dang chudn ddi mpng md.
N5i dung bdi bao gom: Muc 2 trinh bdy cd sd ly thuyet ve tap md, cdc quan he ngil nghia 'd udc lUdng ngii nghia giiia hai tap md. Muc 3 neu cdc dinh nghia vl phu thupc ham md,
>hu thupc phUdng thdc md trgn ldp doi tUdng. Muc 4 dUa ra cac dinh nghia vg d?uig chu^i toi tUdng md 1, 2, 3 vd cdc thuat todn chudn hda ldp vg dang chudn doi tUdng md. Vk cuoi . img la phan ket lu^n.
i:t2 iiiiw \'AN HAN, no CAM iiA, vfi Difc cjii \N<;
2. C O s d LY T H U Y E T
TliiH) Zadeh | l l | . drt hni md <hu.u- nin 1:1 nhi( iiiol. Iiip md Clinf/ la mpt vu liu. m^
m d F t r e u V Xiic dinh hdi hdm lliunc///. . /^ -^ [0,l],t;an nidi phdn IU i/thupc t / m p t ^ i\v (hi ilo iliuor i'u;i 11 \iin lap md /•'. 'IVii) md /•' dUpc U'U'u di?n dirdi dijing
f fipiu) f ={,„,.(l,l)/«l./'F("-i)/"-2./i/-(",l)/",l /'/••(«.,)/"-.} Iiay F = j —^.
Khi / I F ( « ) iluclr xem iiliit .l.i .In Idia liaiiK lua iii.il liieii .V nhan gi& Iri ii. iiiijl gia I diriJe hit'll .lien liiiiin plian '"' ^I'la H'lUli ^•\ "'I't ''i'"
it.v = { t x ( i i | ) / i i i . ii,\ ("a)/i'i,"A:(":l)/":i H,V(II,.)/M..).
trong do. 7r.v(ii,), ii, € t'. bif'ii thi lilia nang .V iiliiiii gia l i | ii,, - \ , A' lan iKVt laen dien bo kha uaiig vii tap uu'I .l.'ii vdi mot gia lii iii.l, Ri") laiif;, 7r,v = F.
Nsil nghia lua dft lien mil TT i i-on ititiJe gcji \k khiing gian ngiT iigiila. ky liifU la ,S',S Cho hai dli lieu ma ITA vii UB. SS{irA] vii SS{nii) lan litot lii Idiiiiig gian ugit nghia riiac N'eu 55(71^) 2 SS{nB)- la noi UA 'iao ham ngil nghia TTB hay ng duoc bao liiun ngir bdi ir.4, Ntii SS{^!.,^) D SSITT,,) vii SS{nA) Q SS(irB). t a iidi SS(n-.4) vii SS(irB) 14 duong ugit nghia vdi nhau |r2|.
Cho [/ = ((/),U2, , .,Un} la tiip vu tru. TT.I vji IZB la hai dit heu nid tren V dita tren bd kha nang, Mi'K d.i nia jr,4 bao ham iigit nghla TT/J. kv hieu .S7 />( - i. 713) diTdc xac din sau [12[:
S/Z3(jr.i,7rB) = ^ min(rrB(Ui). Jr4(u.))/ y" irfl(<l,).
Wli Res la mdt quan he tifdng ditoiig ti.'ii iim'-ii ('. (i(0 ^ Q ^ 1) lil mot iigirdug titiJr vdi Res. Mi'tc do mil TTA 'iao hiun ugrr nghia ng theo qinui he Res ditile xAc dinh nhu si
S/D(7r^,7rfl) = ^ ^ ^^ ^^ mill (irB(uj),?r,i(ti,))/5^irB(uj).
Mfti do tuong duong iigO nghla giita hili dfl lieu md rr^ va irs. ky lii?u la SE{irA,l duoc biciu thi nhu sau[12[
SE[nA,irB) =min{SID(nA,TrB).SID{nB,TtA)).
3. P H U T H U O C H A M M 6 , P H U T H U O C P H U ' O N G T H I J C M C )
Ky hieu OID la tap c ^ dinh daiih doi tuong, moi pli^i tiif ciia GID x ^ dinh duy nli d6i tuong, A la tap hiiu han cac ten thugc tinh, moi phan tu ciia A la t§n ciia mot I
C U I A N I U U C V [,()!' n o i T U O N d TRONC M/OC DO CO Sd llf l.li:U III'dNC D 6 | Tl'd.NC Mf) 133 Tiii) hdp (ric mien gia tri domi.tlonii. . . , d<>iu„{doint la iiii^n gia tri md liav in) dUdc kv hieu la doin.
Ddi tUdiig md. Mnl ddi tupng md la mot bo o = (id. r). id la mpt phdn tu cua OID. r Id mot gid tri md (rd). val{o) bifni Hii gia tri c ddi vdi o. difdc dnili nghia nhu s.ni j4|
(a) mpt phdn tu cua doin. mot pliAii td ciui OID vd ml la cai gid Iri.
(6) neu tfl. ('2 ('„ l.'i cac gid tn va .\[. A> -1,, Id ten CK thudc tinli lln (/i| : r].A_.
V2 A„ : v„) la gid tri bo va {r|. !••> c,,} Id gia Iri lap
Kien (types): Ta cd the dinh nghia mot tdp kien dni tUdng mot each de qui nhu sau:
(1) Kieu dfr lieu nguyen to {la cac .so iiguyon. so thUc Iiav chuoi kv tU cd dp ddi en diuli liiiv thay doi). kieu dii lieu md la mdt kieu ddi tUdng.
(2) Neu T la kieu ddi tUdiig tin .s</(T) la cung la mpt k\6n ddi tupng. Mot dni titdng (6 kien -s(/(r) la mot tap hdp cac ddi tUdng cd kif-ii T..^rt(T) t on dUdc goi la kieu t.i|).
(3) Neu Ti.To r„ la cac ki(^u ddi Iifoiij; tin tiiplc{Ti,Tj....,T,,) lainol kieu ddi tUdng.
Mpt ddi tupng kieu Ti-Ta T„ la mpt )'-bp, trong dd thanh phan tlni i cua ?i-l)6 iiav co kieu T,.fiipl((T\.T> 7',,) cdn dUdc goi la ki^u lid
3.1. Phu thuoc ham m d t r o n g ldp ddi tifdng
Trong cd sd chi lieu ro, phu thuoc ham giiia hai tap thuoc tmh dUdc xdc dinh dua tren phep so sanh bdng giiia hai gia tri tren moi tdp thuoc tinh. Vdi cd sd dii heu md, phep so sdnh bang gifla hai gid tn tien t3,p thupc tuih dUdc tliav bdi miic do tUdng dUdng giiia hai gid tri Clia tap thudc tinh do. Doi vdi CSDL HDT md, kieu dii heu cua cac thupc tinh khong ddn thudn la cdc kieu cd sd ma (6n co cac kien pliifc tap khac nhu kieu tap, kieu bp,... \^i vay, dp tuong dUdng ngu" nghia tren taj) thuoc tinh X cua hai doi tupng Oi, O2 cua idp doi tupng md c{U) duoc xac diiili de qui nhu sau,
(i) Xeii X = {Ai.A> Ah} thi
SE{0i.X.02.X) = mm{SE{0i.Ai,O2.Ai),SE{0i.A2,02-A2).... ,SE{Oi Ak.O2.Ak)), (ii) Xf'ii A, cd kigu ldp cAU,) tin SE{0i.A,.02 A,) - 1 ngn O i . A = Oa-A- Xgucic lai, SE{0i.A,02.A,) = SE{Oi.A, f/,,02.A,.f/,)
(iii) Xgii At Id thupc tinh kieu tap. gia sU Oi-A, — {si,S2,.. .s^, s^}. 02.Ai = {si,S2, Sj ,Sm} thi do tUdng duong ngu: nghia ciia 2 gia tri md Oi.A, va Oa-A dupc tinh nhu sau:
SE(0i.A,02.A.) = max ( m i n (maxfc ( , f ; ° j j 4 * ' ^ ) ) , m i n (max,- ( , f S ! i i - = l . * „ ) ) ) - (iv) Ngu At la thudc tinh nhdn gid tri bo, gia.suOi.A, = {vi,V2,... .v^ ,Vn} , O2.A, = {wi,u;2,- • -^wj, ...,wm} tin: SE{0l.At,02.A^) = miufc (\5='i'^nO"
D i n h nghia 3.1. Cho ldp md c vdi tap cdc thuoc tinh U (ky hieu c{U)); X,Y C U, ldp c thoa man phu thupc ham md X —^ Y ngu VOi, O2 Id cdc ddi tUdng cua ldp c thi
\SE{0i.X,02.X) < SE{0i.Y,02.Y).
iVi du J;Cho ldp c vdi tap thuoc tinh U,X,Y e U, Res{X) vd Res{Y) la hai quan he tUdng
134
tit tren .V vii \ . a\
DOAN VAN BAN. iiA <;AM HA, VO DIIC QUANO
= 0.9, Q2 = 0.9r, lan huft lil hai ngitOng tren Res{X} vii Re.s{Y).
fie,i(.\') a b d
.•
a 1,11
b 0,2 1,0
c 0.3 0.92 1,0
d (1,2 0,-1 0,1 1,0
0,4 1) 1 0,3 0,2 1,0
ne»(Y) f K h
1
1 f 1,0
s
0,3 1,0
h 0,2 11,4 1,11
i 11,90
0,2 0,3 1,0
0,2 0,1 0,4 1,11 Cii.-ll
115 IDI ID2 ID3
(•• lii.li Clia ldp d.'ii titcjng c (lUd<- cho liliU sau.
X {Il7,a.0,4/b.ll,.'i,.'d}
(0 •, 11, 0,4/c. 0,8/d}
III :l/d. 0,8/e}
Y (0,9/f, 0,6/g, l,0/h(
(0,C/g, O.O/li. 0.9/i) {0.0/h, 0,4/i. 0.1/Jt VOi.O; lil
SE(0,-.V,(),,.V) = mm(SID{0,.X,02.X),SID(02.X,Oi..\)) = inin(0.824.0.875) 0,S21 vii SEia,.\.Oi.Y) = nim[SlD(Ox.Y.(h.Y),SID(Oi.Y.Oi.r)) = min(1.0,0.96) 0.96. \ a v S £ ( O i , i ' , O j , V ) > SE{Ox.X,Oi.X). Theo dinh ngliia phi,l thupc hiuu md, ldp tuong md c thoa man phu thuoc / r
B 5 d l 3 . 1 . Cho I6p c{U),X CU,AQU,X Tt). Neu A duac thay Ihi- bdi A^. A,.., , Ak trong c th
md X -^Y.
^ A, gid SIC A : tuple[A\ : T\,A2 : T2....t/
I'. -- 1,2.. ,k.
Chang mmh: ViX -^ A nen vdi Oi, O2 bat ki- tliupc ldp d6i tiioug mdc, ta co S B ( O i . A , |
SE(m.X,02.X) vu vi A dupc thay the bdi Aj.A2. . • .4i nen 1 S E ( O i . / l , 0 2 . / l ) = min(SB(Oi..-l,.0-2,.4,)),i = l..k.
Do do SE{0,.A„02.A,) > SE{Oi.X,(hX}.i = 1..A- Theo dinh nghia phij thuoc 1 md, suy ra X —^ .4i,i = 1,2,.., ,fc,
Dinh ly 3.1. Phu thuoc hdm trong co sd die li$u guan h$ tliod man dinh nghia phu tli hdm md trong CSDL HDT md.
Chiing minh: Clio quan he r{U) thoa man phu tliupc hiun .V —» Y, vdi X,Y C U.
Vfl,(2 e r,ti[X] = t2[X] thi i i [ y | = (2[y|. Gia sir U Va. tap cac thupc tinh ciia ldp mdt V 0 i , 0 2 la. c4c d6i tupng Clia c ta c6: SE{0i.X,02.X) = l,SE{0i.Y,O2.Y) = 1,
Do do, SE(0i.Y,02.Y) > SE{0i.X.02.X). Thep dinh nghia phu thupc ham md ti CSDL HDT ta cd X A Y.
3.2. Tach cac thuoc tinh k i l u bd theo phu thupc h a m md
Tuong tu nhu trong CSDL HDT ro, vipc nhdm mOt sfi thuOc tinh lai t h t o h mOt thupc kieu bd trong mpt ldp co the dan den nipt s6 rang bupc ngii nghia hay phu thudc hau
CHUXN H6A CAC LOP D6I TUONG TRONG LUOC D 6 CO SO D 0 LIEU HUONG DOI TUONG MO 135 giiia cac thuoc tinh khong dupc baa toan [7[, Trong trudng hpp niiy, c^n phai t&ch c4c thupc tinh kilu bp di baxi tpjui c^c rkng bupc ngu: nghla dd.
Gia su; A. : tuple{X, : Ti),i - 1,2,3,... ,lc(it > 1). New A, dupc thay the bdi Xi vii t6n tai phu thupc h i m md X ^ y , vdi X = U XJ,X; C Xi vk V/ C Xt thi .4. : tuple{X, :
1 = 1
Ti),i= 1 , 2 , 3 , . . . . fc dltpc tAch thimh cac tliuOc tinh nhu sau:
Bi : tuple{X,\Xl : Tx,\x'_,i = 1,2,3,... ,k - 1, Bt : tuple(Xi,\Xl\Y : Tx,^^xi\r).i = 1,2,3 fc - 1, C, -.tupleiX', •.Tx;),i = l,2,3 fc,
D:tuple{T:TY).
3.3. Cac luat suy d&n tren cac phu thuoc ham md
Cac luclt suy dan ciia phu tliupc ham md tren ldp doi tupng md c{U), X,Y,ZC U.
Luat 3 1 Phdn xa. NeuX'DY thi X ^ Y . Luat 32 Tdng tnldng. Neu X -^Y thtXZ -^ YZ.
Luat 33 fla'c cdu. Neu X -^Y vdY -^ Z thi X -^Z.
L u a t 34 Hap. Niu X ^ Y vd X -^ Z thi X -^ YZ.
Luat 35 Bic ciu gid. Niu X -^Y vdYW ^ Z thi XW A Z.
,Luat 36 Tdch. Niu X -^Y vd Z clY thi X-^ Z.
D i n h ly 3.2. Cdc ludt suy ddn 3.1 din 3.6 tren ldp dii tuang md la xdc ddng vd ddy du.
I
Viec chiing minh dinh ly tupng tu nhu tnrdng hpp phu thudc hiun md trong cd sd dC li§u quan he md [10, 13].
,3.4. Phu thudc phridng thtfc md PhUdng thdc dinh nghia trong ldp dupc mO ta
*' Mj{N,I,R)^{u,v,g), trong do, N: ten phUdng thdc; / : tap cdc tham so ddu vdo {<ten, kigu>}; R: t^p cdc thupc - :inh ma gia tri cua nd dupc dgc bdi phUdng thiic; u: tap cdc tham so dau ra bao gOm kigu gia :u tra ve {<ten, kiiu>}; v. tap cac thuSc tinh ma gid tri cua nd bi thay ddi bdi phUdng thiic;
r- tap cac thdng bdo dUdc dua ra bdi phuong thiic cd dang {[o,msg,p]}, a Id ndi nhdn thong oao, msg la thong bdo vd p Id tap cdc tham so cd trong thSng bao { < n, t > } .
' Moi quan hg giiia phUdng thiJc vdi cdc thudc tinh dupc xdc diHh thong qua vigc phUdng '^hiic sd dung cdc thuSc tinh dd dg dpc hay siia ddi, Sii phu'thudc ciia phUdng thdc vdo cdc
1 3 G I K ) A N VAN H A N , IU) C A M l l A , VU D d C Q U A N C ; '
thupc linh nlnr tlid duc.ic gpi Id plu.i lliiinc phUdng lliiic md (hi/./.y method dependency*^ vi tat /m-phi,i thuOc")'
D i n h n g h t a 3.2. P^m-phu limpf': CUu Mj la mnt, i)lilft(ng llnic (iia iii(>t, ldp c, yl/^CAf,/,;?) = {u,i\g) vk X = RUi'^0 \k tap cac l,hu()c tinh (doc sda, doi) dif(;c su dijiig bdi Mj. Qua lie giiia M, va \ ttifdc j^pi Id /m-phu l.liiior. ky liirii X —> Mj.
Cac liial SUV dan m a /7n-|)hi,i thupc:
L u a t 37 ,\V» \ ^ ,)/, lui Y -"-> M, Ih, XY M A/,.
L u n t 38 .\. I, X -'-"> M, m X ^"\ Mj Ih, X ^ M,Mj.
L u a t 39 .V, u \ - ^ .\/, vd Y C X thi ) -^ .M,.
L u a t 310 .V, „ MJ gpi dni M, vd X -^ M,,Y ^ M, thi XY - ^ .\lj.
4. CHU A N H O A Ldp DOI T U O N G Md
Tifdiig tu nhu iiio hinh vo sd dd li^u (luan he. trudc khi chuan hda Id]), ta xem xet inOt*|i khai niem nhu phi,i thunc hiun md by phdn. pln.i tliunc ham ino biic ran. khda ciia ldp, tliuOi tinh khda.
D i n h n g h l a 4 . 1 . (Phu LhuOc hdm md ho phdn) Ciio h'Jp (•(('). .V. 1' C ('. 1' dirqc gpi Id phi
D i n h n g h i a 4.2. (Pliy thuof hdm md b;i.c can) Clio ldp c(f/),.V.V. Z C U.Y dupc goi la phu thuoc ham md hdc can vao X neu .V —> Z, Z —^ V va Z ^ X.
D i n h n g h l a 4 . 3 . {Khda ciia ldp ddi tupng md) Cho ldp md c{U),K C U,K dUpc ggi la khda cua ldp doi tugng md c neu thda man hai digu kign sau day:
1. AT A t/, 2. V/f' CK,K' ^ U,
U Id t^p thupc tinh Clia ldp dOi tupng c khong bao gom dinh danh cua ddi tupng.
D i n h n g h i a 4.4. (Thupc tinh khda) Cho ldp md c{U),K Q U,K Id m6t khda cua Idpiwl c, A dudc goi la thupc tinh khda neu Ae K. Nhihig thupc tinh khdng phai la thuOiiu"^
khda goi la thupc tinh khdng khda. |
Clir.AN HOA C.W LCJp DOITlfONC! THONC i.VQC DOCO.Sd DCT 1 111 lllf()\(; DOI ITONC M() 137 4 . 1 . C a c d a n g chuftn ddi tifdng m d
Muc dich Clia cdc diiing chudn tioiig CSDL HDT md (rn) la giai quyet cac van d(- dif tliifa du: lieu va di thudng trong khi thao t.ic drt lieu. Tudng tu < .ii li fiOp can trong |2. 7| trcii ni6 hinh CSDL HDT rd. di.fa tren khdi niem plui thupc ham md tren tap lliunc tinli khong bao gdm dinh danh ddi tupng ciia Idi). ket hdp vdi pintdng phap chudn hda lupc do (|tia(i lie (reii cd sd dli lieu quan he de dUa ra cac dang chuan ddi I Udng md.
D i n h n g h l a 4.5. (Dang clman ddi tUdng mP 1{1F()M')) Ldp c{U) dupc goi la d IFONF ngu V.4 G v. lioac .1 la thunc tuili co kieu lio khong nhan gia tri tap lioai .4 clii chda cac thuoc thih khong cd kieu lip nhan gia tri tap li(ia( .1 khong phai la lliunc tuili khda ki6u bn D i n h n g h i a 4.6. (Dang clnuin ddi tUdiig md 2) (2F0NF) Ldp c{U) dUdc gpi la d 2F0NF neu c d IFONF va khong Inn tai lliunc tinh khong khda A phu thupc ham ind bp phdn van khda.
D i n h n g h i a 4.7. (Dang chudn doi tudng md 3 {3FONF)). Ld]) c{U) dUdc goi Id d 3F0NF neu c d 2FONF vd khong tdn 1^.1 tliud<: tinh khong khoa A phu thupc hdm md bdc can md vao khda.
Mot lupc dd CSDL HDT md dupc gpi hi d IFONF (2F0NF, 3F0NF) neu moi ldp thuoc ludc do CSDL HDT md dOu d IFONF (2F()NF. 3F0XF).
' 4.2. C h u a n h d a ldp doi trfpng m d 4-2.1. Thudt todn chudn hda ldp ve IFONF i \'ao- Ldp ddi tUpng md c{U).
.Ra: Phep tach ldp c thanh cdc ldp r, d IFOXF khong ludt mat thong tin.
' Bu'dc 1. >7'u ldp c cd dang (i), (ii) vk A, khong phai la thupc tinh khda thi ta tach ldp c thdnh 2 ldp c va ci d IFOXF nhu sau'
j ( i ) Clas.s c tuple{Ai : Ti,A2 : T2,... ,A, : sti{t,ipl({X-.Tx)),-• • ,An :T^).
Tach ldp c thanh 2 ldp c \a ci nhu sau
Class c tuple{Ai . Ti. ^2 • T ^ . . . . , A : set{c^),... ,An : T^),
^ Class Cl tuple{X : T\).
(ii) Class c tuple{Ai : T'i,^2 : T 2 , . . . , A : tuple(Bi : h,B2 : h-.-.Bi : set{tuple{X • Tx)),...,Brr,:Tn,),...,An:Trr).
Tach c thdnh 2 ldp c vd cj nhu sau:
Class c tuple{Ai : Ti,A2 : T2,... ,At : tuple{Bi : I^Bz : h, • • • .B, : set{ci)),... ,B^ : T^),...n:Tn),
' Class Cl tuple{X : Tx)-
^ Cdc phUdng thiic phu thupc vko A-i,A2,Az,...,An dUdc phan vdo ldp c. cac phudug thdc jphu thupc vao tdp thupc tinh X dupc phdn vdo ldp ci. Viet lai cac phUdng thilc trong c, ci
cho phil hpp dua vao tdp thupc tinh vd kilu cua nd trong ldp dd.
138 DOAN VAN BAN, Il6 CAM HA, VU DtfC QUANG
Bifdc 2. Neu ldp c cd d^ng (ii), (iii) vd A, Id thupc tinli khda thi ta tdch ldp c thdnh 3 ldp c,ci vd C2 (doi vdi (ii)), thdnh 2 ldp c,ci (ddi vdi (iii)) nhU sau:
(ii) Class ctuple{Ai : Ti,A2 : T a , . . . , ^ : InptfiDi . h,B2 : h,---.Bt : set{tuple{X : Tx)) B„rT^),...,Ar,:T„).
Tdch c tliaiih 3 ldp c,ci va r-j nhif san;
Class c tuple{Ai •.TuA2 •.T2,. • • ,A, •• ci,.. • ,A„ : T„), Class n liiphiB] .h,B2:h,--,B,: srl{r2)),... ,B„t : T ^ ) . Class Cl tiiplc{X : Tx)-
Cdc phudiig thrtc phy thupc vdo >li, A2, ^ 3 , • • • - ^ n dupc phdn vdo ldp c, cdc phuong thiic phu thupc vdo tdp thupc tinh A, dupc phdn vdo ldp r,, cdo phUPng thdc phy thupc vdo tap thupc tfnh X dupc phan vdo ldp 02- Vif-t. l^i lac phUdng thdc trong c,ci,C2 cho phii hpp dya yko tdp thupc tinh vd kieu cua nd trong ldp dd.
(iii) Class ctuple{Ai : Tu A2 : T2,. • •, A,: tuple{X : Tx), • • •, >lf. -Tn).
Tdcli c thdnh 2 ldp c vd ci nhu sau:
Class c tuple{Ai : T i , ^ 2 : ^ 2 , . . . , ^ : c i , . . . , An : T„), Class Cl tuple{X -.Tx).
Cdc phUdng thdc phu thupc vko Ai,A2,A3,...,An dupc phdn vdo ldp r. ckc phudng thflc phu thuBc vdo tap thupc tinh XdUQc phdn vdo ldp ci. Vigt l^ii cdc phUdng thiic trong c,ci cho, phil hdp dua vdo tap thupc tinh va kigu ciia nd trong ldp dd.
4.2.2. Thudt todn chudn hda ldp ve 2F0NF
Vdo: Ldp ddi tupng md c{U) 6 IFONF, F. tdp cdc phu thupc hdm md toi thigu, khda K ciia ldp c.
Ra: Tach ldp c thdnh cdc ldp c, d 2F0NF khong mat mat thdng tin.
Bifdc 1. Vdi moi phu thupc ham md X, A Aj e F. Xj C K vk .Aj la thupc tinh khong khoa {Aj phu thupc ham md bo phdn vao khda K), dat 5, = -V, U Aj. Tao cdc ldp mdi c, vffi tap thupc tinh 5, va khda tUdng dng Id Xj, cac phUdng thdc M phu thupc vdo 5,- dupc dua vao ldp Cj.
Bifdc 2. Ddt U = U — { A } (^i Id cdc thupc tinh phu thnpc ham md bp p h ^ vao klidaiC, tao ldp mdi c{U). Cac phuong thiic M phu thupc vdo U dupc dua vao ldp c{U).
Bvtdc 3. Ddt T la tdp cac ldp dupc tao ra d budc 1. \ d i moi ldp a &T, neu c{U) chtfatap thupc tinh H md H Id khoa chinh cua Cj thi thay tap thupc thih H trong c bdi thupc tinh k cd kigu ldp Cf
Vdi moi phuong thiic M trong cac ldp dupc \igt lai cho phu hdp dua vao cdc thupc tinh vd kigu Clia nd trong IPp dd.
Vi du 2. Cho ldp EMPPROJ mo ta ngUdi 1dm \iec trong cac dy an nhu sau.
Class EMPPROJ ATTRIBUTE
ssn- integer;
CHUAN H6A CAC LOP DOI TUONG TRONG LUQC DO CO sd DC LIEU HUCSNG DOI TUONG MO 139 eName: string;
projNum: integer;
hours: fuzzy integer;
pName: string;
pLocation: string;
WEIGH . . . METHODS
InputEMP(ssn, eName);
ln.putPR03{projNum,pName,pLocation);
InputHour(/iours);
pD: domain[0,l] of real;
END
Tkp phu thupc ham md tren ldp EMPPROJ la F issn -^ eName;projNum -^
pName; ssn —> pLocation; ssn,projNum —> hours \ Khda cua ldp EMPPROJ Id ssn,projNum.
Theo Dinh nghia 1,2, ldp EMPPROJ dd d IFONF nhung khong d 2F0NF vl tPn tai cdc thupc tinh khdng khda phu thupc hdm md bp phdn vdo khda, chdng han eName, pName, pLocation. Tuong tu nhu trong cd sd dii ligu quan hg du thifa dii lieu xay ra khi mpt ngudi 1dm viec trong nhieu du an khac nhau. Ap dung thudt todn chu§n hda ldp ve 2F0NF nhu sau:
Budc 1, 2: Ta cd cac ldp EMPLOYEE (ssn, eName, inputEMP (...)), VKOiBOT {projNum, pName, pLocation, inputPROJ(...)), EMPPROJ(ssn, projNum, hours, mputHour(...)).
Budc 3: Ldp EMPPROJ dUpc chuygn dPi thanh EMPPROJ(employee: EMPLOYEE, project: PROJECT, hours, inputHour(...)).
4.2.3. Thudt todn chudn hoa ldp ve 3F0NF
Vao: Ldp dPi tupng md c{U) d IFONF, F: tap cdc phu thupc hdm md toi thiPu, khoa K cua ldp c.
Ra: Tach ldp c thanh cac ldp Ci d 3F0NF khong mdt mdt thong tin.
Btfdc 1.
Dat S = \JAiv6\ Ax khong cd mdt trong bat ky phu thupc hdm md nao.
Vdi mdi ve trai Xi cua phu thupc ham md trong F, ddt St = Xi\J {Ai}\J {A2} U . . . U {Ak}
trong d d X t -^ Ai,Xi -^ A2,...-,Xi -^ Ak la cac phu thupc ham md trong F.
Vdi mPi Si tgo ldp mdi Ci(5,) vdi khda Id Xi, cdc phUdng thiic M phu thupc vdo iS", dupc dua vdo ldp Cj. '
Btfdc 2.
Dat T la tap cdc ldp c, dudc tao ra d budc 1, neu khong tPn tai mpt ldp ci cd khda K thi tao mpt ldp mdi c b ^ g cdch bP sung t$,p thupc tinh S vdo c, e T ma cd khda {K — S). Cac
140
^^:i?t.il!
DOAN VAN HAN, 116 CAM llA, Vfl Dt'/C Q U A N G phuong thdc M phy th"0<' vim A' (\^i<.'f pl'dn vim Idp r{K).
BvCdc 3.
Wli mdi ldp r, G T. neu r, • (> khda H ma / / C AT I lii I hay t ap thupc tinli H trong c boi thupc tinh h vu kien Idp c,.
\V)i mni phUdng thi'rc M Irniig cac ldp dupe vlcl hii c'lio phii hpp dya vdo cdc thupc tmh va kien ciia nd trong ldp d<'t.
Tlm^t toan tdch ldp r thiinh cac ldp d IFONF. (2F0NF. 3F().NF) la khong lam mdt mat thong till. Ta c6 I IK'' kiPm tra vivv tacli ldp r{U) llidnh cac ldp a Id khdng lam m i t thong tin dya vao Bn dg 2 trong |7|
Vi du 3. Clio Idp Teacher nhu sau:
Cla.ss TEACHER .\TTRIBITK
,S,SH: integer;
iNaiiic string;
salary: fuzzy real;
dept: string:
dName: string;
dLocation: string;
WEIGHT: . . . METHODS:
InputTEA(ssTi, fiVamc,sa/ary);
InputDEPT(dept, dName, dLocation);
pD: domain[0,I] of real;
EXD.
Khda cua ldp Teacher Id ssn
Tdp php thupc hdm md tren ldp Teacher F = <ssn —^ tName]ssn - A salary; ssn —>
fc fc 1 dept; dept —*• dLocation, dept —*• dName >.
Theo Dmh nghia 12, ldp TEACHER dd d IFOXF nhimg khong d 3FOXF vi ton tai cac thupc tinh khong khda phy thupc ham md bdc can vao khda, chdng han dName, dLocation,.
Cling nhu trong cd sd du: ligu kinh dien. di thudng khi xda bp xuat hien khi xda mpt Khoa nao dd thi thong tin cua tat cd cdc Gido vien trong khda dd se bi mdt di. Ap dung thudt toan chudn hoa ldp vg 3F0NF nhu sau:
BuPc 1,2: Ta cd cac ldp TEACHER(ssn, tName, salary, dept, inputTEA{...)), DEPARTMENT (dept, dName, dLocation, inputDEPT{...)).
Budc 3: Ldp TEACHER dupc chuygn ddi thdnh TE ACHER(ssn, tName, salary, deparir^
DEPARTMENT, inputTEA( .)), phUdng thdc inputDEPT(...) phu thudc vao thuDciinb department cd thg bo di.
CHUAN HOA CAC LOP D6I TUONG TRONG LUOC DO CO s6 DO Liiiu iidONG DOI TUONG MO 141
^. K f i T L U A N
MPt lUdc dp CSDL HDT nid/ro ban dau cd thg ditpc thigt kc chua tot cd thg dan d6n du thifa dli hpu. Su du thifa dit lieu lain tPn li^i d6n thih toan vpn thi hgu. GiPng nhu cac cd sd dd ligu khac, dg ngudi thiet ke c6 dUpc nipt lupc dd CSDL HDT md thich hpp can phai xem xet cac phu thupc dii heu trong moi ldp ddi tuong. Cac php thupc dii h?u Id tri tlnic ngii nghia vg the gidi thuc vd dupc xem nhu cdc rdng bupc todn ven doi vdi vice (hict ke. Tudng tu nhu trong cd sd du lieu quan he rd (md), cd tho dua cdc d^ng chudn ddi lupiig md vd cac thuat toan chudn hda ldp doi tupng \ e IFOXF. 2FOXF. 31-{)XF dg hd trd cho ^•iec tliiet kg CO sd du: lieu doi tupng, dPi tuong quan hp. Tren cd sd bdi bdo iiiiy, php thupc dudng dan va phUdng phdp truy vdu doi tupug di.ra ticii dudng dan trong CSDL HDT md se dupc trinh bay trong nghign ciiu tiep theo.
T A I LIEU T H A M K H A O
[1] B.Bouchon-Meunier. Hd Thudn. D$iig Thanh Ha. Logic md vd Ung dung, Dai hoc Quoc gia Ha Npi, 2007.
[2] Byung S.Lee. Normalization in OODB design, ACM SIGMOD Record 24 (3) (1995) 23-27.
[3! Catriel Beeri, Ronald Fagin, and John H. Howard, A complete axiomatization for functional and multivalued dependencies in database relations, Proceedings of ACM SIGMOD, August, 1997 (47-63)
[4| Christophe Lecluse. Philippe Richard, Fernando Velez, O2 - an object-oriented data model.
Proceedings of the ACM SIGMOD 17 (3) (June 1988) 424-433.
[5] Gloria Bordogna, Gabriella Pasi, Recent Issuse on Fuzzy Databases, Physica-Verlag Heidelberg New York, 2000.
[6] GilUan Dobbie, Toward normalization on object-oriented databases, "Technical Report CS-RS- 96/16".
[7] Nguyen Kim Anh, Chuan hoa sd dO co sP dfl lieu huPng doi tupng, Tap chi Tin hpc vd Diiu khiin hpc (2003) 125-130.
[8] P. J. Pratt and J. J. Adamski, Database Systems Management and Design (3"* edition), Boyd k FVaser Publishing Company, Danvers, MA, 1994 (597-598).
[9] M, I. Sozat, A. Yazici, A complete axiomatization for fuzzy functional and multivalued depen- dencies in fuzzy database relations, F\izzy Sets and Systems (2001) 161-183.
[10] Tarek Sobh, Advances in Computer and Information Sciences and Engineering, Springer, NewYork, 2008 (300-304).
[11] L. A. Zadeh, Fuzzy sets, Information & Control 8 (3) (1965) 338-353.
I12] Zongmin Ma, Fuzzy Database Modeling with XLM, Springer, NewYork, 2005.
Ngdy nhdn bdi 6 - 4 ~ 2011
