Download - TTNT-04-NguyenLyHeuristics
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TR TU NHN T OCc nguyn l Heuristics
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N i dung trnh by2Bi ton th a mn rng bu c (ConstraintSatisfaction Problems)Bi ton t i u
Thu t gi i leo iLuy n thp
Thu t gi i di truy n
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Bi ton th a mn rng bu cCho t p cc bi n V1, V2, , Vn. M i bi n Vi cth nh n cc gi tr t mi n DiM t c u hnh l m t php gn gi tr cho ccbi n V =d V =d V =d d thu c D
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Cho t p cc rng bu c C1, C2, , Cm. Rngbu c l m t yu c u trn c u hnhC u hnh h p l l c u hnh th a mn ccrng bu c
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th rng bu c4
Vi
Ci
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V d - Bi ton n H u5
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V d - Bi ton t mu6
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Bi ton t i u haM i c u hnh h p l c hm nh gi Eval(X)Tm c u hnh h p l t i u (Eval(X) nh nh tho c l n nh t)
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hnh t i u m khng c n quan tm n ng i
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V d v bi ton t i u ho
Thi t kM ch i n
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C r t nhi u chip c nh Cng s k t n inhng t n t khnggian hn
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V d v bi ton t i u ho (tt)9
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Tm ki m c c bTm ki m c u hnh h p l t t. Khng tm ki m ng i.T c u hnh hi n t i xem xt cc c u hnhln c n.
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Khng m b o tm c c u hnh t i u.R t hi u qu .
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Cc v n c a tm ki m c a bM c k t m t
c c tr aphng
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Khng th dichuy n ra kh icc vng ph ng
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Thu t gi i leo i (Thu t gi i thamn)
Leo i: C g ng t i a ho Eval(X) b ng cch dichuy n n c u hnh cao nh t trong t p dichuy n c a mnh Leo i d c ng
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L p
Tm tr ng thi con S c a S v i Eval(S) cao nh t N u Eval(S) khng cao hn Eval(S) th
return SNg c l i S = S
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V dGOAL
b c a2
81
2
25
h=8
h=5 h=4
h=0
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START
d
pq
e
h
f
r
9 913
534
4
15
1
2
h=12
h=8
h=6
h=9
h=4
h=6h=11
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Cc bi n th c a leo i
t S := tr ng thi ban u L p sau m t MAX l n c g ng no
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Leo i ng u nhin
L y m t tr ng thi con ng u nhin S c a SN u Eval(S) cao hn Eval(S) th S= S
Cu i l pReturn S
Sau khi ch y vil n c th a n
tr ng thi ch
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Cc bi n th c a leo i (tt)Leo i v i kh i t o ng u nhin nhi u l nLocal beam search:
Theo di k tr ng thi cng m t lc
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T i m i l n l p, t t c tr ng thi con c ak tr ngthi c pht sinhN u xu t hi n tr ng thi ch th d ng l i; ng cl i ch nk tr ng thi con t t nh t t ton b danhsch v l p l i
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Luy n Thp1. t X := c u hnh ban u2. t E := Eval(X)3. t i = di chuy n ng u nhin tmoveset4. t Ei := Eval(move(X,i))
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5. i X := move(X,i)E := Ei
Ng c l i v i xc su t no ,ch p nh n di chuy n ngay c khi
m i chuy n x u hn:X := move(X,i)E := Ei
6. Quay l i 3 n khi k t thc.
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Luy n Thp (tt)1. t X := c u hnh ban u2. t E := Eval(X)3. t i = di chuy n ng u nhin tmoveset4. t Ei := Eval(move(X,i))
Chng ta s ch n xcsu t ch p nh n m t dichuy n t i hn nh thno?
Xc su t = 0.1
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5. i X := move(X,i)E := Ei
Ng c l i v i xc su t no ,ch p nh n di chuy n ngay c khi
m i chuy n x u hn:X := move(X,i)E := Ei
6. Quay l i 3 n khi k t thc.
Xc su t gi m theo th igian
Xc su texp (-(E - Ei )/Ti ): Ti l
tham s nghi t
Tng t nh qutrnh lm l nh trong
luy n thp v t l
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Thu t gi i di truy n c gi i thi u b i John Holland nm 1975,
cho php th c hi n tm ki m ng u nhinM ho cc l i gi i tm nng c a bi ton b ngcc nhi m s c th
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n g c a c c g qua cnghi c a cc nhi m s c thLu tr m t qu n th cc l i gi i ti m nng
Th c hi n cc php ton di truy n pht sinhcc c th m i ng th i p d ng ch n l c tnhin trn cc l i gi i
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Thu t gi i di truy n (tt)
Pht sinhqu n th ban
u
Xc nh thch nghi c a
qu n th
Tho i uki n k tthc?
K t thc
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Ch n l c Lai ghp
Xy d ngqu n th m i
t bi n
Xy d ng qu n th k ti p
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M t s cch bi u di n gen c th gi i bi ton b ng thu t gi i di truy nta ph i gen ha c u trc d li u c a bi ton.C hai cch bi u di n gen:
1. Bi u di n gen b ng chu i s nguyn (hay th c)
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o VD: B i to n 8 h u -> 125348672. Bi u di n gen b ng chu i nh phn
o VD: Bi ton 8 h u: dng 8 x log28 bit bi u di no Lm sao bi u di n nghi m th c b ng chu i nh phn
???o Tr l i: R i r c ho mi n tr v i m t chnh xc cho
tr c
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Cc khi ni m c b n t t c a m t c th
L gi tr c a c th cho m t v n bi ton cth .V d : Trong bi ton t i u c c i m t hm f, n u
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c n m c m ng m c a o n m cth cng t t khi lm cho gi tr hm cng l n.
xc nh c t t c a cc c th ta c n
m t hm lm vi c ny. Hm ny g i l Hmm c tiu .
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Cc khi ni m c b n (tt)Hm m c tiu
Dng nh gi t t c a m t l i gi i ho c cth .Hm m c tiu nh n vo tham s l gen c a m t
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c th v tr ra m t s th c.Ty theo gi tr c a s th c ny m ta bi t c t t c a c th .
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Cc khi ni m c b n (tt) thch nghi c a cc c th (fitness)
L kh nng c th c ch n l c vo th hsau ho c l c ch n l c cho vi c lai ghp t o ra c th con .
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V thch nghi l m t xc su t c th cch n nn ng i ta th ng nh x thch nghivo o n [0,1 ] ( thch nghi chu n)
==
N
ja jF
a iF a iF 1
)(
)()( i = 1,2N
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Cc ton t c b nTon t lai ghp:
Cc c th c ch n lai ghp d a vo d avo thch nghiDng qui t c bn quay rollete:
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Vd: cc ta c qu n th v i thch nghi chu n sau
STT C th TN chu n1 0010001 0,42 0010101 0,33 0101000 0.054 1100011 0.25
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Cc ton t c b n (tt)Ton t lai ghp:
L y gi tr ng u nhin p [0,1] ch n c th laighp, c th c thch nghi cao c xc xu t l ach n nhi u hn
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,cc nhi m s c th t i v tr ng u nhin v i xcsu t pc
Ton t lai ghp c xu h ng ko qu n th v
pha cc c th c thch nghi cao => c c b a phng
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Cc ton t c b n (tt)Ton t t bi n:
Gip l i gi i c th nh y ra kh i cc c c tr aphngV i m i c th trong qu n th , th c hi n t bi n
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v i xc su tpm t i m t v tr ng u nhin (thngth ng pm
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V d : Gi i phng trnh b c hai
Xc nh kch th c qu n th :n= 4
Ch n phng php m ha nghi m:
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Xc nh nghi m nguyn trong mi n tr : [0, 31]M ho theo chu i nh phn: s bit m ho =5
L a ch n hm thch nghi
Hm thch nghi = 1000 (X2 64), ch nnghi m c h s thch nghi ~ 1000
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V d : Gi i phng trnh b c hai(tt)
Xc nh kch th c qu n th :n= 4
Ch n phng php m ha nghi m:
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Xc nh nghi m nguyn trong mi n tr : [0, 64]M ho theo chu i nh phn: s bit m ho =5
L a ch n hm thch nghi
Hm thch nghi = 1000 (X2 64), ch nnghi m c h s thch nghi ~ 1000
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V d : Gi i phng trnh b c hai (tt)
Pht sinh t p qu n th ban u
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p n g m1 00100 42 10101 213 01010 104 11000 24
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V d : Gi i phng trnh b c hai (tt)
Tnh h s thch nghi (Fitness) cho qu n th
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STT Nh phn Nghi m X2
64 H s thch nghi1 00100 4 -48 10482 10101 21 377 6233 01010 10 36 9644 11000 24 512 488
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V d : Gi i phng trnh b c hai (tt)
Ch n l c nghi m v lai ghpCh n nghi m 4 v 10 ti n hnh lai ghp v i xc su t
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44 0010010000
1010 0100101010
0100100000 88
0010011010 66
c
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V d : Gi i phng trnh b c hai (tt)
t bi n m t c th
V i m t xc su t pm t bi n l i gi i th 4 v i v tr
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pos= 4
0000111010 66 0011111010 1414
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V d : Gi i phng trnh b c hai (tt)
Tnh l i h s thch nghi cho nghi m m i v ti n hnhch n l c
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STT Nhphn Nghi m X2
64 H s thchnghi1 00100 4 -48 10482 01010 10 36 9643 01000 8 0 10004 01110 14 132 868
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i u c n n mHi u bi ton th a mn rng bu c, bi ton t i
uHi u c cc thu t gi i tm ki m c c bHi u c thu t gi i leo i, leo i ng u
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nhinN m c cc v n c a leo iHi u c cc t ng ng sau Luy n thp
Hi u v n m c cc b c th c hi n c aGA
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Th c m c35