chuong 2 - tac tu

Tr Tu Nhn To

Nguyn Nht Quang

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Vin Cng ngh Thng tin v Truyn thngTrng i hc Bch Khoa H Ni

Nm hc 2009-2010

Ni dung mn hc: Gii thiu v Tr tu nhn to

Tc t nh ngha Mi trng cng vic Cc kiu mi trngg Cc kiu tc t

Gii quyt vn : Tm kim, Tha mn rng buc

Logic v suy din

Biu din tri thc

Suy din vi tri thc khng chc chn

Hc my

Lp k hoch Lp k hoch

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Tc t - nh ngha g Tc t l bt c ci g (con ngi, ngi my, software

robots, cc b n nhit,) c kh nng cm nhn (nhn bit) , , ) g ( )mi trng xung quanh n thng qua cc b phn cm bin(sensors) v hnh ng ph hp theo mi trng thngqua cc b phn hot ng (actuators)qua cc b phn hot ng (actuators)

Tc t con ngi Cc b phn cm bin: mt, tai, v mt s b phn c th khc Cc b phn hot ng: tay, chn, ming, v mt s b phn c

th khc

Tc t ngi my Tc t ngi my Cc b phn cm bin: cc my quay (cameras), cc b truy tm

tn hiu hng ngoiCc b phn hot ng cc loi ng c (motors) Cc b phn hot ng: cc loi ng c (motors)

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Tc t v Mi trngg

Hm tc t: l hm nh x t lch s nhn thc ti cc hnh ng:

f: P* A Chng trnh tc t: hot ng (chy) da trn kin trc

thc t ca hm f

Tc t = Kin trc + Chng trnh4Tr tu nhn to

V d: Th gii ca my ht bi

Cc nhn thcCc nhn thc V tr v mc sch s V d: [A, Bn], [B, Sch]

Cc hnh ng Di chuyn (my ht bi) sang tri, sang phi, ht bi, hoc khng

lm g clm g c

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Tc t my ht biy Bng hnh ng ca tc t my ht bi

Chui cc nhn thc Hnh ng g[A, Sch] Di chuyn sang phi[A, Bn] Ht bi[B, Sch] Di chuyn sang tri[ , ] y g[B, Bn] Ht bi[A, Sch], [A, Sch] Di chuyn sang phi[A, Sch], [A, Bn] Ht bi[A, Sch], [A, Bn] Ht bi. . .

function Reflex-Vacuum-Agent( [location,status]) returns an actiong ( [ , ])if status = Dirty then return Suckelse if location = A then return Rightelse if location = B then return Leftelse if location = B then return Left

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Tc t hp l (1)p ( ) Tc t cn phn u lm ng vic cn lm, da

trn nhng g n nhn thc (nhn bit) c v datrn nhng g n nhn thc (nhn bit) c v da trn cc hnh ng m n c th thc hin

Mt hnh ng ng (hp l) l hnh ng gip cho tc g g ( p ) g g pt t c thnh cng cao nht i vi mc tiu t ra

nh gi hiu qu hot ng: l tiu chun nh gi th h t h t t t tmc thnh cng trong hot ng ca mt tc t

V d: Tiu ch nh gi hiu qu hot ng ca mt tc t my ht bi c th l: mc lm sch, thi gian ht bi, mc in

nng tiu tn, mc ting n gy ra,

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Tc t hp l (2)

Tc t hp lp Vi mi chui nhn thc c c,

Mt tc t hp l cn phi la chn mt hnh ng Mt tc t hp l cn phi la chn mt hnh nggip cc i ha tiu ch nh gi hiu qu hot ng ca tc t ,

Da trn cc thng tin c cung cp bi chui nhn thc v cc tri thc c s hu bi tc t

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Tc t hp l (3) S hp l S thng sut mi th

S thng sut mi th = Bit tt c mi th vi tri thc v hn S thng sut mi th = Bit tt c mi th, vi tri thc v hn V cc nhn thc c th khng cung cp tt c cc thng tin lin

quan

Cc tc t c th thc hin cc hnh ng nhm thay i cc nhn thc trong tng lai, vi mc ch thu c cc thng tin hu ch (v d: thu thp thng tin, khm ph g ( p g ptri thc)

Tc t t tr (autonomous agent) l mt tc t m cc h h t h bi h h ki hhnh ng ca n c quyt nh bi chnh kinh nghim ca tc t (cng vi kh nng hc v thch nghi)

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Mi trng cng vic PEAS (1)

PEAS Performance measure: Tiu ch nh gi hiu qu hot ng

Environment: Mi trng xung quanh

Actuators: Cc b phn hnh ng Actuators: Cc b phn hnh ng

Sensors: Cc b phn cm bin

thit k t t t th i h (h l) t ti thit k mt tc t thng minh (hp l), trc tin cn phi xc nh (thit lp) cc gi tr ca cc thnh phn ca PEAS

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V d: Thit k mt tc t li xe taxi t ng

h i hi h t (P) t h h nh gi hiu qu hot ng (P): an ton, nhanh, ng lut giao thng, mc hi lng ca khch hng, ti u li nhun,

Mi trng xung quanh (E): cc con ng (ph), cc phng tin khc cng tham gia giao thng, nhng ngi i b, cc khch hng, g g g

Cc b phn hnh ng (A): bnh li, chn ga, phanh, n tn hiu, ci xe,

Cc b phn cm bin (S): my quay (cameras), ng h tc , GPS, ng h o khong cch qung ng, cc b cm bin ng c,

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V d: Thit k mt tc t chun on y tnh gi hiu qu hot ng (P): mc sc khenh gi hiu qu hot ng (P): mc sc khe

ca bnh nhn, cc tiu ha cc chi ph, cc vic kin co,

Mi trng xung quanh (E): bnh nhn, bnh vin, nhn vin y t, Cc b phn hnh ng (A): hin th trn mn hnhCc b phn hnh ng (A): hin th trn mn hnh cc cu hi, cc xt nghim, cc chun on, cc iu tr, cc ch dn,

Cc b phn cm bin (S): bn phm nhp vo cc thng tin v triu chng, cc tr li ca bnh nhn i vi cc cu hii vi cc cu hi,

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V d: Thit k mt tc t nht vt

nh gi hiu qu hot ng (P): t l (bao nhiu phn trm) cc vt c t vo ng cc thng

Mi trng xung quanh (E): dy chuyn chuyn ng trn c cc vt, cc thng ng

Cc b phn hnh ng (A): cnh tay v bn tay c kt ni

Cc b phn cm bin (S): my quay (camera), cc b cm bin cc gc (cc hng)

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V d: Thit k mt tc t dy ting Anh tng tc

nh gi hiu qu hot ng (P): cc i ha im thi ting Anh ca hc vin

Mi trng xung quanh (E): mt nhm hc vin

Cc b phn hnh ng (A): hin th mn hnh ccCc b phn hnh ng (A): hin th mn hnh cc bi tp, cc gi , sa (cha) bi tp

Cc b phn cm bin (S): bn phmCc b phn cm bin (S): bn phm

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V d: Thit k mt tc t lc th rc (spam emails filt i )filtering)

nh gi hiu qu hot ng (P): kh nng lc th ( t f f l iti f l ti )rc (amount of error: false positives, false negatives)

Mi trng xung quanh (E): email server and clients

Cc b phn hnh ng (A): nh du th rc, gi thng bo

Cc b phn cm bin (S): nhn v phn tch ni dung cc emails

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Cc kiu mi trng (1)g ( ) C th quan st c hon ton (hay c th quan st c

mt phn)? Cc b cm bin ca mt tc t cho php n truy cp ti trng thi y

ca mi trng ti mi thi im

Xc nh (hay ngu nhin)? ( y g ) Trng thi tip theo ca mi trng c xc nh hon ton da trn

trng thi hin ti v hnh ng ca tc t (ti trng thi hin ti ny) Nu mt mi trng l xc nh, ngoi tr i vi cc hnh ng ca ccg g g

tc t khc, th gi l mi trng chin lc

Phn on (hay lin tip)? Kinh nghim ca tc t c chia thnh cc giai on (chng/hi) Kinh nghim ca tc t c chia thnh cc giai on (chng/hi) Mi giai on bao gm vic nhn thc ca tc t v hnh ng m n

thc hin mi giai on vic la chn hnh ng thc hin ch ph thuc vo mi giai on, vic la chn hnh ng thc hin ch ph thuc vo

giai on (khng ph thuc vo cc giai on khc)

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Cc kiu mi trng (2) Tnh (hay ng)?

Mi trng khng thay i trong khi tc t cn nhc (xem nn Mi trng khng thay i trong khi tc t cn nhc (xem nna ra hnh ng no)

Mi trng bn ng (semi-dynamic) l mi trng m khi thigian tri qua th n (mi trng) khng thay i nhng hiu qugian tri qua th n (mi trng) khng thay i, nhng hiu quhot ng ca tc t th thay i V d: cc chng trnh tr chi c tnh gi

Ri (h li )? Ri rc (hay lin tc)? Mt tp hu hn cc nhn thc v cc hnh ng, c nh

ngha phn bit r rng

Tc t n l (hay a tc t)? Mt tc t hot ng c lp (khng ph thuc / lin h vi cc

tc t khc) trong mt mi trngtc t khc) trong mt mi trng

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Cc kiu mi trng V dChi c Chi c khng Li xe taxi tnh gi tnh gig g

Quan st y ? c c khngXc nh? chin lc chin lc khngPhn on? khng khng khngPhn on? khng khng khngTnh? bn ng c khngRi rc? c c khngT t ? kh kh khTc t n? khng khng khng

Kiu ca mi trng c nh hng quyt nh i vi vic thit ktc ttc t

Mi trng trong thc t thng c cc c im: ch c th quanst c mt phn, ngu nhiu, lin tip, thay i (ng), lin tc, atc ttc t

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Cc kiu tc t

4 kiu tc t c bn

Tc t phn x n gin (simple reflex agents)

T t h d t h h ( d l b d fl Tc t phn x da trn m hnh (model-based reflex agents)

Tc t da trn mc tiu (goal-based agents)

Tc t da trn li ch (utility-based agents)( y g )

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Tc t phn x n gin (1)p g ( )

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Tc t phn x n gin (2)Tc t phn x n gin:

H h th t t (l t) i ki h hHnh ng theo mt quy tc (lut) c iu kin ph hpvi trng thi hin thi (ca mi trng)

function SIMPLE-REFLEX-AGENT(percept)static: rules (tp cc lut c dng: iu kin-hnh ng)

state INTERPRET-INPUT(percept)rule RULE-MATCH(state, rules)action RULE-ACTION[rule]return action

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Tc t phn x da trn m hnh (1)

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Tc t phn x da trn m hnh (2)

Tc t phn x da trn m hnh: S dng mt m hnh ni b gim st trng thi hin ti ca S dng mt m hnh ni b gim st trng thi hin ti ca

mi trng La chn hnh ng: ging nh i vi tc t phn x n gin

function REFLEX-AGENT-WITH-STATE(percept)static: state (m t trng thi hin ti ca mi trng)

rules (tp cc lut c dng: iu kin hnh ng)rules (tp cc lut c dng: iu kin-hnh ng)action (hnh ng gn nht)

state UPDATE-STATE(state action percept)state UPDATE-STATE(state, action, percept)rule RULE-MATCH(state, rules)action RULE-ACTION[rule]

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return action

Tc t da trn mc tiu (1) Bit v trng thi hin ti ca mi trng: cha

Cn bit thm thng tin v mc tiuCn bit thm thng tin v mc tiuTrng thi hin ti ca mi trng: mt ng t, xe taxi c th r

tri, r phi, hoc i thng

Thng tin v mc tiu: xe taxi cn i ti ch n ca hnh khch

Tc t da trn mc tiu Tc t da trn mc tiuTheo di trng thi hin ti ca mi trng

Lu gi mt tp cc mc tiu (cn t c)u g t tp cc c t u (c t c)

Chn hnh ng cho php (rt cuc) s t n cc mc tiu

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Tc t da trn mc tiu (2) ( )

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Tc t da trn li ch (1) Trong nhiu mi trng, thng tin v cc mc tiu khng nh gi hiu qu ca cc hnh ng nh gi hiu qu ca cc hnh ngC rt nhiu chui cc hnh ng cho php taxi i n ch (tc

l t n mc tiu)

Nhng: chui hnh ng no nhanh hn, an ton hn, ng tin cy hn, chi ph thp hn?

Cn s nh gi li ch i vi tc t

Hm li ch (utility function)nh x t chui cc trng thi ca mi trng ti mt gi tr s

thc (th hin mc li ch i vi tc t)

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Tc t da trn li ch (2) ( )

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Tc t c kh nng hc (1) Kh nng hc cho php tc t ci thin hiu qu hot ng ca nng ca n

4 thnh phn to nn mt tc t c kh nng hc Thnh phn hnh ng: m nhim vic la chn cc hnh ng

Thnh phn nh gi (bnh lun): nh gi hiu qu hot ng

Thnh phn hc: gip ci thin hiu qu hot ng - da trn cc nh gi, thay i (ci thin) thnh phn hnh ng

Thnh phn sn sinh kinh nghim: c nhim v xut cc hnh p s s g c ut cc ng gip sn sinh ra (dn n) cc kinh nghim mi

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Tc t c kh nng hc (2)g ( )

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C s tri thc ca tc t Mt c s tri thc (a knowledge base) l mt tp cc mnh

(pht biu) c biu din trong mt ngn ng hnh thc, cung cp tri thc (hiu bit) cho mt tc t

Tc t khai thc c s tri thc (m n s hu) trong qu trnh a ra cc hnh nga ra cc hnh ng

Cc tc t c th c xem xt mc Tri thc: Tc t bit nhng g? Cc mc tiu ca tc t l g?

Ci t h thng: Cc cu trc d liu trong c s tri thc? Cc gii thut Ci t h thng: Cc cu trc d liu trong c s tri thc? Cc gii thut s dng cc tri thc ny?

Tc t cn c kh nngTh th ( ht) t i th i Thu thp (cp nht) cc tri thc mi

Cp nht vic biu din (bn trong tc t) i vi mi trng xung quanh Suy din ra cc thuc tnh n ca mi trng xung quanh

S l h h h l Suy lun a ra cc hnh ng hp l

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a tc t (1) Mi trng hot ng: Cng tc (hp tc) hay l Cnh

tranh (i khng)?tranh (i khng)?

Trong nhiu bi ton thc t, mi trng hot ng lun thay i (bin ng) tc t cn cp nhtthay i (bin ng) tc t cn cp nht

Cn mt m hnh biu din k hoch ca cc tc t khc

Cc tc t cng tc Cng chia s cc mc tiu hoc cc k hoch V d: Lp k hoch (cho hot ng nhm) trong tr chi tennis V d: Lp k hoch (cho hot ng nhm) trong tr chi tennis nh i

Cc c ch cng tc: Phn tch v phn phi cc nhim v cho mi tc tmi tc t

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a tc t (2) Cc tc t cnh tranh

V d: chi c V d: chi c Mi tc t phi nhn bit c s tn ti (v hot ng) ca cc

tc t khcMi t t t h t (d ) k h h ( t ) Mi tc t tnh ton (d on) c cc k hoch ca (mt s) cc tc t khc

Mi tc t tnh ton (d on) c nh hng ca cc k hoch t t kh i i k h h b th ca cc tc t khc i vi k hoch ca bn thn n

Mi tc t quyt nh hnh ng ti u i vi d on nh hng ny

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Tc t - Tng ktg Tc t tng tc vi mi trng thng qua cc b phn cm

bin v cc b phn hnh ng p g Hm tc t m t cc hnh ng m tc t thc hin trong

cc tnh hung Mt tc t hp l s cc i ha hiu qu hot ng ca n Cc chng trnh tc t ci t (thc hin) cc hm tc t

C t PEAS h i t i Cc m t PEAS xc nh mi trng cng vic Cc mi trng c phn loi da theo cc tiu ch: C th

quan st c? Xc nh? Phn on? tnh? Ri rc? Tc t q n l?

Cc kin trc tc t c bn: Phn x, Phn x theo trng thi Da trn mc tiu Da trn li chthi, Da trn mc tiu, Da trn li ch

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chuong 2 - tac tu

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