Tong Quan Vetri Thuc

  • Published on
    11-Dec-2015

  • View
    217

  • Download
    2

Embed Size (px)

DESCRIPTION

Trit hc

Transcript

<ul><li><p>TRI THC V MT S PHNG PHP BIU DIN TRI THCTng quanMt s phng php biu din tri thcX l tri thc khng chc chn</p><p>TS. Phm H ThyKhoa CNTT- i hc Nng Nghip HN</p></li><li><p>Tng quanKhi nim v tri thcPhn loi tri thcBiu din tri thc</p></li><li><p>Khi nim v tri thcTri thc c nh ngha trong Oxford Dictionairies:facts, information, and skills acquired by a person through experience or education; the theoretical or practical understanding of a subject. awareness or familiarity gained by experience of a fact or situation.nh ngha trong Bch khoa ton th Vit NamTri thc l kt qu ca cc qu trnh nhn thc ca con ngi v i tng c nhn thc, lm ti hin trong t tng con ngi nhng thuc tnh, nhng mi quan h, nhng quy lut vn ng, pht trin ca i tng v c din t bng ngn ng t nhin hay h thng k hiu khc. </p></li><li><p>Khi nim v biu din tri thcBiu din tri thc( knowledge representation): cc phng php din t v t chc tri thc trong my tnh cho cc h thng tin c tnh cht tr tu my c th tin hnh cc php lp lun t ng.Trong tr tu nhn to, cc phng php BDTT thng c s dng nh lgic v t, mng ng ngha, biu din khung, lut dn. </p></li><li><p>Phn loi tri thc(knowledge classification)procedural knowledge-Descriptive knowledge) Explicit knowledge -Implicit knowledgeCertain knowledge Uncertain knowledge</p></li><li><p>Tri thc th tc Tri thc m t Tri thc th tc (producedural knowledge) l tri thc m t cch gii quyt mt vn , quy trnh x l cc cng vic, lch trnh tin hnh cc thao tc Cc dng ca tri thc th tc thng dng l cc lut, chin lc, lch trnh VD: - Cc bc gii mt phng trnh bc 2; cch lm bnh chng,... </p><p>Tri thc m t (Descriptive knowledge) l mt khng ng v mt s kin, hin tng hay mt khi nim no trong mt hon cng khng gian hoc thi gian nht nh. V d: khng nh v hin tng: Mt tri ln phng Ty. Khi nim v: tam gic u: l tam gic c ba gc bng nhau; H ni l th ca Vit Nam; Tng l k s ca nh my; Nhit ngy 20/8/2013 l 33o....</p></li><li><p>Tri thc n- tri thc hinTri thc hin(Explicit knowledge)l nhng tri thc c gii thch v m ha di dng vn bn, ti liu, m thanh, phim, nh, thng qua ngn ng y l nhng tri thc c th hin ra ngoi v d dng chuyn giao, thng c tip nhn qua h thng gio dc v o to chnh quy.Tri thc n(implicit knowledge)l nhng tri thc thu c t s tri nghim thc t, dng tri thc ny thng n trong mi c nhn v rt kh m ha v chuyn giao, thng bao gm: nim tin, gi tr, kinh nghim, b quyt, k nng... </p></li><li><p>Tri thc chc chn- khng chc chnTri thc chc chn (certain knowledge): l nhng tri thc chc chn ng.VD:-khng nh:tng cc gc trong mt tam gic bng . -Nu hng h thng in th xe my khng khi ng c.Tri thc khng chc chn(uncertain knowledge): l nhng khng nh, lut suy din khng chc chn ng.VD:-Khng nh:Nu bnh nhn b st cao v ho th bnh nhn b vim phi.-Nu xe my khng khi ng c th xe my b hng b in. </p></li><li><p>Cc hnh thc chia s tri thcTri thc c th c chuyn giao v chia s. C th chia cc hnh thc chia s tri thc thnh bn dng chnh:n - n: Khi ngi chia s v ngi tip nhn giao tip trc tip vi nhau (v d: hc ngh, giao tip, ging bi...) th vic tip nhn ny l t tri thc n thnh tri thc n. Tri thc t ngi ny khng qua trung gian m chuyn ngay thnh tri thc ca ngi kia.n - Hin: Mt ngi m ha tri thc ca mnh ra thnh vn bn hay cc hnh thc hin hu khc th li l qu trnh tri thc t n (trong u ngi ) tr thnh hin (vn bn, ti liu, v.v.).Hin - Hin: Tp hp cc tri thc hin c to ra tri thc hin khc. Qu trnh ny c th hin qua vic sao lu, chuyn giao hay tng hp d liu.Hin - n: Tri thc t dng hin tr thnh dng n. in hnh qu trnh ny l vic c sch. Hc sinh c sch (tri thc hin) v rt ra c cc bi hc, tri thc cho mnh (n).</p></li><li><p>Mt s phng php biu din tri thcBng vn bn Bng logic v tBng mng ng nghaBng frame (khung)</p></li><li><p>Cc phng php biu din tri thcBiu din bng vn bn, bng ghi m, bng ghi hnh -M t tri thc bng cch vit ra trong mt vn bn, hoc bng li ghi vo bng c th kt hp hnh nh minh ha VD: sch gio khoa,bng ghi cch dy nu n x l c tri thc loi ny cn c cc cng c phn tch cu, hoc on vn bn.</p></li><li><p>Biu din tri thc bng logic mnh , logic v t Thng qua cc qui tc biu din v x l mnh , v t, cc lut sn xut, lut suy din-VD: inh ngha cc v t LH(x,y):x ln hn y,CTG(a,b,c): a, b, c l cnh ca mt tam gic...-Lut sn xut: If A then B (A B)-Cc cu Horn chun l cc lut c dng: Head:- Body tng ng vi Body Headvi Head l mt v t cn Body l mt tchca cc v t.Vd: IsDiv(X,6):IsDiv(X,3),IsDiv(X,2).(c ngha Nu X chia ht cho 3 v chia ht cho 2 th X chia ht cho 6)- Cc lut suy din: lut modus ponens Nu AB v A ng th suy ra B ng</p></li><li><p>Biu din bng mng ng nghaPhng php s dng cc nt ch cc i tng v cc mi tn ch mi quan h gia cc nt. V d:</p></li><li><p>VD:Mng ng ngha dng gii bi ton:cho 2 gc A,B v cnh a, tm ng cao hc.</p></li><li><p>Biu din bng khung (Frame)Mi mt i tng tri thc c biu din thng qua mt khung gm cc slot (m t cc thuc tnh ca i tng) v cc facet m t cc gi tr, hoc cc th tc tnh cc gi tr. </p></li><li><p>Frame :CIRCLE(hnh trn)r : radius;s : area;p : perimeter;d : diameter;d = 2 r;s = pi r2;p = 2 pi r;</p><p>FrameRECTANGLE(hnh ch nht)b1: side;b2: side;s : area;p : perimeter;s = b1 b2;p = 2 (b1+b2);d2= b12+ b22;</p></li><li><p>X l tri thc khng chc chnTri thc khng chc chn(uncertain knowledge): l nhng khng nh, lut suy din khng chc chn ngV d:- nhit ngy mai l 32o - Nu xe my khng khi ng c th bugi b hngTuy khng chc chn nhng nhng tri thc khng chc chn quan trng v cn thit trong i sngCn thit phi c phng php biu din v nh gi</p></li><li><p>Mt s phng php biu din tri thc khng chc chnBiu din bng xc sutBiu din bng h s chc chn</p></li><li><p>Biu din tri thc khng chc chn bng xc sutXc sut ca mt s kin P(A) =</p><p>V d: gi A l s kin xut hin mt chn khi gieo mt con xc sc 6 mt, Khi P(A)=1/2Trong thng k: Xc sut ca mt s kin A c o bng t s s ln xy ra v tng s ln quan st VD: khi thng k 1000 ngi dn th thy c 1 ngi b mc bnh lao phi. Nu gi A l s kin mt ngi b mc bnh lao phi. Khi P(A) = 1/1000 = 0.001=0.1% </p></li><li><p>Xc sut c iu kinP(A/B): XS s kin A xy ra vi iu kin s kin B xy ra.(i khi ngi ta gi A l gi thuyt, B l bng chng. P(A/B) o mc ng ca gi thuyt A khi c bng chng B)VD: Xt lut: AB B- bnh nhn b st A bnh nhn b cm Khi ta c P(A/B) = 0.45(Trong 100 trng hp BN b st th c 45% l b cm)Xt lut ngc li : BA Ta c P(B/A) = 0.85 (trong 100 trng hp BN b cm th c 85% b st) </p></li><li><p>Cng thc Bayes</p><p>Trng hp A,B c lp th P(A/B)=P(A)</p><p>Cng thc tng qut:</p></li><li><p>V d: Mt bnh nhn c triu chng st v ho (B). Cc gi thuyt l A1: bnh nhn b vim phi; A2: bnh nhn b cm. Xc nh xem kh nng no ln hn.Gi s ta c: P(B/A1) = 0.8 ; P(B/A2) = 0.2. ng thi ta c P(A1) = 0.005 v P(A2)=0.001.Khi : P(A1/B) = 0.8*0.005/(0.8*0.005+0.2*0.001) = 0.95238 P(A2/B) = 0.2*0.001/(0.8*0.005+0.2*0.001) = 0.04762Nh vy c th khng nh rng 95% l bnh nhn vim phi.</p></li><li><p>Biu din tri thc khng chc chn vi h s chc chn H s chc chn(Certainty Factors- CF)CF(Fact) [-1,1]S kin (Fact) cng gn -1 th tin tng s kin l ng cng nh S kin (Fact) cng gn 1 th tin tng s kin l ng cng ln.Xt lut R: A BGi A l iu kin, B l kt lun ca lutTa c h s chc chn ca K, ca lut v ca kt lun. </p></li><li><p>Qui tc tnh HSCC ca iu kinTnh HSCC ca iu kin:CF ( K1 And K2) = Min[CF(K1), CF(K2)] CF (K1 Or K2) = Max[CF(K1), CF(K2)] V d : CF(bnh nhn b st) = 0.9 CF(bnh nhn b hc hi) = 0.6 =&gt; CF(bnh nhn b st And bnh nhn b ht hi) = 0.6 =&gt; CF(bnh nhn b st Or bnh nhn b ht hi) = 0.9 </p></li><li><p>Qui tc tnh HSCC ca kt lunXt lut R: K KL Khi : CF(KL) = CF(R) * CF(K)</p><p>Khi c nhiu lut suy ra cng kt lun: R1: K1 KL vi CF1(KL) R2: K2 KL vi CF2(KL) </p></li><li><p>Tnh HSCC trng hp mt kt lun suy t nhiu lutV d : CF(bnh nhn b ht hi) = 0.8 CF(bnh nhn b st) = 1 CF(If bnh nhn b ht hi Then bnh nhn b cm) = 0.5 CF(If bnh nhn b st Then bnh nhn b cm) = 0.6 =&gt; CF1(bnh nhn b cm) = 0.4 =&gt; CF2(bnh nhn b cm) = 0.6 =&gt; CF(bnh nhn b cm) = 0.4 + 0.6(1 0.4) = 0.76 </p></li><li><p>Ti liu tham khoWiig, K. (1993). Knowledge management foundations. Arlington, TX: Schema Press.Malhotra, Y. (2000). Knowledge management and virtual organizations. London: Idea Group Publishing.Wiig, K. M. (1997). Roles of knowledge-based systems in support of knowledge management. In J.Liebowitz&amp; L. C. Wilcox, Knowledge management and its integrative elements(pp. 69-87).New York: CRC Press.Nguyn Thanh Thu(1999).Tr tu nhn to: Cc phng php gii quyt vn vxl tri thc. Nh xut bn Gio dc.Nguyn Thin Thnh (2006).Bi ging tr tu nhn to v h chuyn gia,i hc Bch khoa Thnh ph HCM https://db69bfee-a-3a390da7-s-sites.googlegroups.com/a /ptvuong.com/cac-he-co-so-tri-thuc/tai-lieu/C3-Bieudientrithuccoban.pdfhttp://vi.wikipedia.org/wiki/Tri_th%E1%BB%A9c http://www.knowledge-management-tools.net/ http://oxforddictionaries.com/definition/english/http://bachkhoatoanthu.vass.gov.vn/ </p></li></ul>