HAL Id: inria-00510152
https://hal.inria.fr/inria-00510152
Submitted on 13 Oct 2010
HAL is a multi-disciplinary open access archive for the deposit and dissemination of sci- entific research documents, whether they are pub-
L’archive ouverte pluridisciplinaire HAL, est destinée au dépôt et à la diffusion de documents scientifiques de niveau recherche, publiés ou non,
Accurately Detecting Symmetries of 3D Shapes
Aurélien Martinet, Cyril Soler, Nicolas Holzschuch, François X. Sillion
To cite this version:
Aurélien Martinet, Cyril Soler, Nicolas Holzschuch, François X. Sillion. Accurately Detecting Sym-
metries of 3D Shapes. [Research Report] RR-5692, 2005, pp.30. �inria-00510152�
ISRN INRIA/RR--5693--FR+ENG
a p p o r t
d e r e c h e r c h e
Thème COG
INSTITUT NATIONAL DE RECHERCHE EN INFORMATIQUE ET EN AUTOMATIQUE
Accurately Detecting Symmetries of 3D Shapes
Aurélien Martinet, Cyril Soler, Nicolas Holzschuch and François X. Sillion ARTIS - GRAVIR/IMAG - INRIA
N° 5692
Septembre 2005
.+/ 02143656748:9<;=0?>@568A74>CBEDGF0H563JIKL3M7N0NB O+56P4KL36;=Q*R+KL3MSNQ2PUTV/ PWT<;X8 Y:Z[0@;=8 \4KL5MQ^]`_EI563M3M5MK=8
.acb*d?Ifegha.Jijda+kXd?9:.gleGdO+adm.
nporqHstvuwxzy|{C}~q?s^tH~J 4r~
Wt?J np{
JWr=4Jt(t2ortHort= 4y {CtHtHsG rtGW¡4¡4y|N¢%£ tH~
¤¥A¦H§?¨U©rª§«(¬ t£4XN~tWjWrs*W®s^tor¯4p°££±r *~}Cs^s^t±tH~pW ²³´~o£=tH~HµNo£UJ®~?µ
®~4s^t®W£~¯s*~¶o£±oj·±tH@¸t(*~oXW=t 4·± £W·±·±}r£o£Wr 4tHº¹nportH~t%~}Cs^s^t±tH~JWt(tt?»
s^±r±~®?··±}¼¯rXhorr 4ohort^£~tW-±4t?s^tH®Ut^½N£WN}=¾cort^ 4t?rt?W·±±¿?tHhs^s^tH4~H¹
À}vt?ÁrWs^£r (o£tJt?ÁCt?s*(£*~£ort?±HW·roXWs4r®Ct?±t?4~EWLortH~tJs^s^tH4~Hµ4¶tJtHU¸t?
ortp£WWs^t?t?~W£ort~}Css^t?t2~AW£ort~o£W=t4¹npo£tp?s^rU4G¯ ·®W t?s^=4~Ãts^rt?·®~
®~Es^4tJt±t?N N}£~±r (or®~E±¯s*U4±W*Xt?s^t?4W·XW·± 4o£sHW£ r·tLtHU¸tH±r
ort~}Cs^s^t±tH~G¶or·±tc~o£W=t£~±r Go£t~}Cs^s^t±tH~WÃ~p~r »Ä£~?¹ Årr·±±HU±X~W!or®~
¶4Ævr tp¯4sÇ4ort?t?NEt?s^tH~or±r (L 4t?4st?}G¶Ão*tH~=tH[(ort~}Css^t?t2~[º%~o£W=t4µ
^ tHs^t®c4s£t2~~4VµCNtH··± 4t?NJst2~ojtH±r W£4s*U®cX~W4±W±V¹
ȼÉNÊLËÌvÍ ¨@ÎA¦4«Ï ~~¸t³cU~t~?µ£{C}Cs^s^t±tH~Hµ£xctHs^t}У~W£±r
¦ « X~!£4XN~4£~Vrrts?orrtWs*U±½Nrt=4r®t?N°£t? ·t2~A~}Cs±tH~At¯s^tH~
²4³GµLM¹t¹(·±tH~c®~4s?t2~½Nr ·®W®~~tGrrtv¯4s^tv ·± XW·±t?s^t?N±N¸U®4t4¹%ut2~c~}Ns?t2~~N»
t?s±HtH~+ts*Wr±q?thr2®~t ·W®t-t··±®~W± r£t-½N£WN±4t?s2®W±t ¾Vt2~
s^s^tH4~E ??W·±®~2~?¹! EtÁrWs^±£WNE·t2~[t?ÁNt?s*ct?·t2~E?Ct±t?N~"o£s^4r±½Nrt2~[~roH®½NrtH~
t?tH~%s4s^t?4~?µAr4£~%tr¸4£~c·±tH~%£sq?tH~(t2~G~}Cs±tH~%t·®¯4s^t¹#!jtHort?o£t
t~}Cs?t2~(=r%·±tH~%s^q?·±tH~Gs^r·±tÁt2~t2~Gt?£ tÂ?4t* %$?t&j··±®~W± t?tH~(±»
¯4s*U4£~pr£~p£j· 4Ãors^tcX'?s^t?NW·6µrHW£ r·±tt(t4r¸t?p·t2~~}Cs±tH~"rrt¯s^t
tH ±·±±~WNG·±tH~G~}Cs±tH~%rt~tH~G~£~»6£t2~?¹(!tH~GW£r·®?W±£~Gt?t*@¸UW±·4£tHrtH4G·t
t?s*W±·±·± tG?oHt?Ntv·® )Hs±tGt?-t2~=t2mW4c·®+~}Cs±ttH~cs^q?·±tH~HµL·®+s^rtH~~±4
?s±½Nrt4µC·HrÃ4±4tH··±± t?Nt%t(s*W±··®W 4tH~tJ·£~£®U44s^W®½Nrt¹
*´Í §H¦ Ë ª+ ¦+« Ï ~~t(t%³Å4r?t2~?µX{C}Cs±tH~HµÐ£~WX®U±jtGx,?s?t
0 1
!A#&+#%
Ï N}~o£W=t2~W£- tHs^t®?·As^t?·®~tÁor± rà #! 2!"# ¾(±~s^t®GWX~¯4s*~Åo£U%·t22¸t
ort¼~oXW=t ·± £··±}`££oXWr 4tHº¹43Å~£ `~}Cs^s^t±tH~HµrtjHW s*Wr±rr·®Uts^rt?·®~s^t+t?»
?tH4·±}ho£4r o`o£t?t?4(t?s^tH~or±r 4±4t?·±·± tH4%s^tH~o t2ã jr 4Ws*~H¹*wÅort?(=t?N®W·
rr·±±HU±X~±£·±£tps^tH·4s^rt2~~±VµU?£~®~t?4AtÁC£t?»6s*W£rr XµUs^tH·4s^r·t?±Vµ£
4s^W®±£~4±W±V¹
nport~}Ns^s^t±tH~Ws^rt?· Wtv~4s^t±s^tH~s*t@¸UW±·®W r·±t% C}ort?t2U4ÅWEo£tvs^tH·Mµ
£vtHrt2~tH4tHGt?ÁC£·®·±}Go£t°X·tp¯s*U orts^tH·®~ t?ÁC£t2~~tHG±V¹53Å~£··±}µor@¶t?¸t?2µUor®~
®~rWortcH~tµCW£Wrs*W®W£~·®U±4£~E =t¶tHt?°£·±tůs*U~s^s^£·}^tH~£·Ãortc·N~~
or®~r¯s^W±V¹76£J~?W£rtH+s^t?·®~Hµr~}Cs^s^t}±¯4s*U±+®~·®~s^®~~£ C}£Urt¹
Ð*or±~£W=t?2µN¶tÅ£t2~tH4W·± 4ors o£WpWs*U®?W·±·±}vt±t?¸tH~~}Cs^s^t±tH~±G t?»
s^t®?·Xs^tH·M¹wrpW·± 4orsÇ®~±£t?=tH£t?NpWVortt2~~t?·®U4Wºortcsrt?·8C£®r·®W2µ
tH~Er~~£sto£Uortsrt?·Xo£4~E =tHt?*t2~~t?·®UtH^±(s*W£rt?X~®~t?N¶oortc~}Cs»
s^t±tH~J¶tGUt?s^Å*®tH4¯}4µ=W£jÃŶÆC~¶t?·±·!j£®~}4 tHm~J~£o¼4~J~HWr£tHs^t?·®~H¹
wr· 4Ãors £~tH~*rt?¶<C·6µrort 9:<;=.>?$ ¯r£±£~H¹JJWortHJo£h?s^rr
ortH~t¯r£±£~ptÁr·±®·±}µ¶t±tHm·}s^rrtort?±~rort?®?W·Lo£Ws^r®Ct?±t?4~?µ£~±r ^
4~(W£-??rWt%tHorr®½Nrt¹GnporttÁCt?s*WEortH~tv¯r£m4£~£¼o£t?±~rortH®?·oXWs4r®
?Ct±t?N~ptH£W r·±t£~ptt?s±r®~®?W·±·±}t2U¸t?ort%~}Css^t?t2~ ^~o£W=t¹
6rG?s^=4~Ãt~o£=tH~Hµ!6¹t¹~o£W=t2~ £r·G C} ~~tHsG r·±r h~±s^r·±t?G~£mrtH~Hµ!¶t±s±¿?t
ortv4s£W±¼ N}jrr·±}Cr *ort%°£~·± ors ortv~r »Ä£W~Hµro£t?ht?U¸4t?·±} £r·®±r
ort~t?WV~}Css^t?t2~EWLort4s^=4~ÃtJ~o£XtJWÆC±r %NvH4r4 =o*ortÅt?·®U¸tJ=4~±£~
ort%~r »Ä£W~W£ort?±t?·®U±¸tc±t?4U4£~?¹
¬ tptHN¸C®~±vs*WC}%rr·±±HU4£~¯ 4r ¶ÆLµU±£·±£±r tHs^t®4s^rt2~~±VµWX~®~t?N
s^tH~ot2ã *£Ws*W®±£~WN®U4V¹
npor±~£=t?®~p4 NWr±¿?tH+~¯4··±@¶J~H¾ ±ort¯4··±@¶±r *~t2m4Vµ¶t(t?¸CtH¶ rt?¸C±£~p¶Æ*4
®t?N¯}Cr j t?4s^t®G~}Cs^s^t±tH~4 W³ £²4³Ç~o£=tH~H¹(nportH- ~tHm4-²rµº¶trt2~tH4
U¸t?¸CtH¶ AortG~}Ns^s^t}N»ÐttH±jr4 r·±t?s W£ortv½N£WN±tH~J£~tHj¼4rÅ· 4ors*~?¹Ð
~tHm±A@Xµ2¶tE±4r£t[o£tE 4t?rtH·±¿?t2s^s^t?N~W££Vs^torcÅ4s£tEortHs<tÂ?tH4·±}98
±f~tH±'-¶t¼rtH~t?4r· 4Ãors ¯4*®t?4}C±r ~}Css^t?t2~?¹ nportjt?ÁCt?X~± Wcor®~
· 4ÃorsÇ^?s^=4~Ãt~o£=tH~®~£t2~tH4t2j~tH±r¹76A±£W·±·±}µ±~tH±¼¢%¶t~orU¶ ~s^t
tH~r·~WXWrr·±®?U4£~ArJ· 4Ãorsj¹
B C
? ED#%GF
·±}vW£rNortH~A%~}Css^t}vttHm4¯?£~t2ort³'r r·±t?sj¹ ·±oIH<J2LKNNMĵ ¬ ·tH
t?W·6¹OHPJHQK4NM£SRÅ 4or£WsTHPJHQK4 M£t2~tH4^s^t?orr~ tHr£t+orth³J»Ð~}Cs^s^t} t?t2m±
r r·±t?s UJH³ £Wt?hs*Uor±r £4 r·tHsjµX¯¶or®oht?Â*?tH4~·±4htGÆCrU¶VHWCo
t?(W·6¹5JHC¢¢=MĹ(npo£t?±· 4Ãors*~Åt?Â*?tH4·}t?tH(·· =N~~ £·t^~}Cs^s^t±tH~± +=±4(~t2µº rr
tco£ 4or·}+~t?£~øtc^r4±~t¹
t?4¯}N±r +~}Cs^s^t±tH~¯²³s^t?·®~J®~JsG£o¼s^t%?s^r·±tÁjWX·±·tGtH~tHWojor®~
~r tHmo£~ =t?tHr£ r·®~ortHº¹YX4±r W£+À£rÆt2HPJH4/JMX£t2~tH4p~}Cs^s^t}ttHm±+st?orrºµ
tH~±t2v%WW±£·£~}Cs^s^t}4µ4 £~tH^%~ort?s^t?··±tH tHrt?UtJ£t2~µ4°£~°££±r
oC}N=ort?®?·~}Css^t}UÁtH~Hµrort?¸t?ï}C±r ^ortH~tv~~£s±£~H¹npor®~Ås^to£j®~Å £~tHj4h
4rot?£t2~tH4W±WA~4·®srt?·º££~tH~ 4ro*ort?4}4¹ npo£ttH=t?£tH£} =t?жtHt?+or®~
4ro»6t?rtH~t?NU±GW£%ortps*Wr£r c =t¶tHt?v=4N~As*ÆtH~!ort?± s^torGor± o£·}%rt?=t?£rt?4
4`ort=4·4 }Worts^tH~o £ ~t?£~±¸t*-~s*··srð=?U4£~%Wport tHv tHs^t}4¹
À~~^W£ W£rt? H¡¡L@Mr@¸C®t¼ s^rt?·¯ tHrt?W·J²³ 4 Ct2m~W£ ±¸t¼W'W·± 4ors
+tH~%r 4£t?£?tG(~}Cs^s^t}j¯4ortH~t4 Ct2m~H¹vnport?±(W£rNoh±~(?WXW r·±tvt±t?¸C±r
~}Css^t?} rX~%WÅ W rÃ} ~oXW=t r®~W·®~¼=4·4 }N»ÄtH=t?£tH42µ ~±£tt?·±t2~%4
s*rr±r j =t?жtHt?`=±4~(Wort*s^rt?·6¹{NW±r ¯4s W rmt?t^t?rtH~t?4U4Vµ Ï ±r@¸C®
t?J·M¹ HPJH4²MºtH~± =t· 4Ãors £4~t24mt?t?»M@¸t?~W·=^®t?N¯}+~}Cs^st?t2~pW ^²³
4 Ct2mH¹ npo£t?±· 4Ãors t?·±t2~G u °££ ortj?W£r±rWtUÁ®~8pu or@¶t?¸t?G·®~G
®t?N¯}WÁCt2~¯v·± 4t?·±4~~!4 Ct2m~?µX·±£±r or± or·±}~}Cs^st?± tH~p~£o~tH r·®W
~·±±£~?¹
J·±·!ort2~tGs^torr~J}*°££h~±~}Css^t?t2~p¯4²³s^tH·±~H¹~Å?£~tH½NrtH£t4µrortH}
th~tH£~±¸tj £®~th£frW`±s^=t?¯tHm4£~?¹LW rr~ÆC} t?+W·6¹ HPJH44 MJrt°£rt st2~rt
~}Cs^s^t}j¯4rr»6=t?¯tHs^t?·®~HµVt?°£rtH 4~ort^s^±rsG£s Ws^rN¶ÆjtH½Nr±tH¼
£~¯4s ~o£W=tN~}Css^t?±~o£=t¹Anpor±~As^torGt?·±t2~%ortp r·±Ð}Å°X~At2~W r·±±~o
?tH~=£tH£tc =t¶t?tH=4N~Hµr¸tH}tH~±±¸tcrtH?£±!¹
{Cr W£'{CortHWo HPJH4N¢=MJ£~t¼ort 9>L.> #.#!""! )Q ®t?N¯} ~}Cs^st?t2~^ C}
·±CÆC±r (W?tH·±W±£~ ±^ortcxW£~~®W^±s*W t4¹A~E Ï rU¸C®ptW·6¹,H<J2²M6µUort?}t?·±}G4^u
¼±tH4ï} =Wt?4±·UÁt2~W~}Ns^s^t}4µVoN£~%=N~~ £·}hW±·±r ¼4 or± o£·} ~}Cs^s^t®4 Ct2m~H¹
Ï 4t*t2t?N·±}µ W(W¿Ho£r-t?vW·6¹YH¡¡L@M[±4r£t2ort #! 2! >L#!- $# µ[¼4··±tH±
~rort?®?W·¯rXm±X~!oXU t2~?± =tEorts^tH4~rtW£Åsrt?·~WW±£·4W£%t$#£tH±¸t~}Css^t?}
¶o tH~=tHm tH¸t?}fUÁ®~X~~±r orr 4ofort tH4tH+%s*~~?¹Çnport?±st?or rU¸N®t2~
4CtH~r·~p±+ort%~o£W=t±rt?4ð=?U4Vµr rJ±N¸4·¸4tH~p^~r?tc±4tH U4¯4tH4oj~Ws^r·±tH
±tHm4 8or±~~r4t±4t? U±®~HW±tHv4*(¸@Át?·r 4®º¹53Å~r (ortÅ~}Cs^st?}tH~r~
J±tH4ï}(~}Ns^s^t±tH~VtH½Nr±t2~VW%HrUtE~Ws^r·±±r ±%··4rtH±£~Hµ2s^ÆCr ortHAW·± 4ors
¸tH} 4~·±}f¯¼W<??rUt ~t?jWvtH~r·Ã~?¹ÐzN~HµÅ4rj· 4Ãors r·±} 4s^rt2~j
t?t?s^±r±~®+~s^··NrsG =tHW~£4tNtH W·®~?µ ¶or®o t=t?¯s^tH ortj~o£=t~t?·µ
£-~·±·[rU¸C±rtH~¸t?}h??rUtvtH~r·~H¹ %LtH±¸t*4s£·t?ÁC}h4s^£W±~£~Ŷ±·±· =t^ ±¸t?-
{Ct2m±4IKr¹
& &('%p)'^?OD
u4£~®t?±r ~r?t
S
µ ort # !"!# WS
t*ort+±~s^t?±*W£~¯s*~%¶or±o s*S
44`~t?·µ±'WN} C4±£Wtj~}~tHs ?t?4t?tH 4 Ã~t?NtH*W 2¸CÐ}4¹'{C}Cs^st?±tH~^
~o£W=t¯s r ¯vort·®2¶ J££m4 ?s^=4~Ã4Vµ[¶Ão ®t?NÐ} ~vÃ~vrtHW·tH·t?»
s^t?NH¹ 6r^ 4±¸t?¼~o£W=t4µro£tG~£}[~£oh^ 44rt?·®UtH~p*ortvs*W±j[s^WortHs^W®?·
?}~W·±·± WroN} HEXt%¡¡L@MĹ
nport^ r-Wortr =t4µº¯4±£~£tµ44X~
48
tH·tHstH4~+*~t?t6A± rt?J-,¾ort^®tH4}µ tH 4o43 −
¯·®U4£~W££4
=N~~± r·tWÁCt2~?µNr±rt4 −
¯·®W±£~4r£3
=4~~± r·±tUÁtH~Hµπ
2π 3 π 2
π
2π 3 π
2
6A± rt J¾ Ï 4»Ð~}Css^t?t2~W£¼U±£W·»Ð~}Ns^s^t±tH~¯4r£¼ N}4rW·± 4o£s¯cr =t
*¯¯J?·±}µrWÅW·±·ºtH·tHstH4~JWtctHrt2~tH4tH ,¹
~ÃÁ
2 −
¯·®-WU4£~Wr£6
=N~~ £·t*UÁtH~HµVr±rt*s±4»Ð~}Css^t?t2~cW£°rt?tH`Wort?(t?·±t»s^t?N~4 rt2+ N}+4s^XN~±r WU4£~pW£+s^±»Ä~}Ns^s^t±tH~?¹
{N£}C±r *o£t( 44rW ®~s^t±tH~
IR 3
~orU¶J~po£W¯4Å^ ±¸t?j®~4st?}I
µrort?t%W·±¶@}~t?ÁC®~~+4or£s^W·L £4~®~
( X , Y , Z )
±4^¶or®oort(s^WÁWI
ÆtH~ort¯4··±U¶r ¯sj¾I(λ, α) =
λ 0 0
0 cos α − sin α 0 sin α cos α
¶o
α ∈ [0, 2π[
λ = ± 1
~ ~r 4tH~t2( C}ortptÁrsr·±tW£ortr =tµWor®~[4tH~=£r~V
3
%Lt?t?NE·®~~t2~WX®~4st?t2~?¾WU±X~?µWs^4»Ð~}Cs^st?t2~A£vortHs^=N~±Vµ4t?=tH£±r (¶ortort?
λ
±~[=N~±¸t£
α = 0(
s^π)
¹U6A£rr -h~}Cs^st?}-Jh~oXW=t*oC£~GtH~·±¸tH~(Nh°££±r -¼¸t2m4X
y¶or®o¼¶tv?W·±·Vort #
ortG®~4s^t}y|£¼Whr ·±t
α
y|¶or®o¼¶tv?W·±·Vort<
W ort
®~4s^t}^y ~£o+o£U
I(λ, α)
s*£~o£±~J~o£W=t44^~t?·¹RJU¶t?¸tHHµr°££±r W·±·~}Cs^s^t±tH~JW[~o£W=t(®~JsG£o¼s^t%Âr·Åo£¼~±s^r·}jort2ÆC±r
¶ort?ortHGj ±¸t?-£~¯4s 4m£W·±·±}h®~%¼~}Cs^s^t}4¹Ð`£W®£·±cort£W±¸t*rr4ooXU
¶4r·®G4£~±~AXortHÆC£ c~As^N}%~Ws^r·±tHG¸UW·±rt2~W
( X , λ, α)
4~=N~~ £·t°££vc~}Cs^s^t}®~pC*N~·}4¹ ¬ toNX~rt?t2^t?t?s^£±~®cs^t?or+^°££ CrHW£®rWtH~H¹
wrEWr£No%c°££rr %~}Css^t?t2~ £~tH~[±4tHs^t2±WtJ½N£WNÐ}4µ4?··±tHGort 9:<;=.>
$ ¯rXm±X~[W=ortÅ~o£=t¹Anpo£tH~t¯r£±£~E¶·±·r =tpo£tp4r®L~t2m4@£¹ À}Gt?Ás^r±r
ortH~t½N£4Ãt2~%¶t¶±··rt?¸t± {tHm4 ¼tt?s±r®~±· 4Ãors ¶or®o`°X£r~vj°££Ãt
CrsG =t?(=4~~± r·±t^?£®rUtH~¯
X
µλ
WXα
¹^ÀtH?£~t^~s^trN¶pW4tH±r·±t~¸U·£tH~s*@}W£=tHWArr Åortr?tH~~?µHortH~tHW£®rWtH~AWt[o£t?vortHÆtH( £4Æ(ort± ±£W·4~o£W=t4¹
Ð`ort+~Xt2°XH~t*WJhtH4·~}Cs^st?}"*
λ = − 1
WXα = π
,mµ ~o£r·®` =trtH`o£WN}tH±¼HWj =t(ort # W ortv~}Cs^s^t}H±r *ortvW =U¸t(t?°£r±V¹ RJU¶t?¸tHHµ
or±~~=tH°Xv?4~tCtH~rWtH½Nr±t%°££±r N}j£st?t?~Å£h¶·±· ~±s£·}¼ =t£tH¼ort
HW£®rUt(~}Cs^s^t±tH~*o£tHÆ*¯4H¹
{Cs^t~o£W=tH~%orU¶t?¸tH%s*2}- =t $N#! ~}Cs^st?±µ W£ ?s^rr ~}Cs^st?t2~¯4%ort2~t
~o£W=t2~£~±r ort t?£t?W·±¿HtHs^s^tH4%££m4£~%Wort¶or4·t~oXW=t*s^@}r@¸4t^£4?£Wtµ
r£?£ *¯4±£~W£?t%·±~tG=N~±¸tH~H¹c ~tH?£h44± r4hWEor®~£=t?®~Å~o£@¶zoXU
~}Css^t?t2~A?Wv·±~Å =t¯££G N}%?£~£m¸4t· 4Ãorsjµ@ N}%~t?£Wt?·±}?s^rr ort~}Cs»
s^t±tH~pWA~r »Ð4s=4rt?N~AW+4 Ct2m£~±r vo£tc°£~st?orrºµrt?t?s^£r ortHJ~±s±·®WÃ}
rG®~4s^t®pW£~¯s*U4£~?µ4£~~?±W±r or®~r4s*W±^vs^rrt~}Cs^st?t2~E
ort%¶o£·±t%~o£W=t4¹pnpor®~Å?£~£m¸4t%W·± 4ors £CU¸tH~p =t%s^4t%4??rWt4¹Ä±~Årt2~tH4t2
±¼{tHm4jr¹
p % #G v"
Ðho£±~~t2m±¶tvN£?tvrt?¶·®~~ÅW[¯££m4£~?¾ort
: <;=.> $ "#
W~o£W=t4¹
¬ tort?~orU¶ o£Wort2~t¯££m4£~o£2¸4t±4t?tH~±r %t?·®W±£~or±£~[¶Ão*ort~}Ns^s^t±tH~EWLort
~o£W=t4µrW£o£Uort?}£U¸C±t(Wt$%LtH±¸t(st?orr^t?±t?¸t~£o¼~}Cs^s^t±tH~H¹
6£J*~£4t
S
±¼^²W»Ä±s^t?£~±£·º4s^±Vµ¶t%t°£rt%Ã~ 9:<;=.> $ , At?2p
±tHm4
ω
N}M 2p (ω) = Z
s ∈S k s × ω k 2p ds
* J-,Ðor®~Jt°£r4Vµ
s
±~J¸tH¶or±o·±±rÆ~ort(?t?Nt?JWA @¸N}*Wo£t(~o£W=t+*r·±4t2Uport4± ± ,+*=±44jort~r?t%£
ds
®~oN£~c*±°£rt2~±s*W·A~rt%tH·tHstH42¹M 2p
Ã~tH·Ã®~^±tHm±£W·L¯r£±V¹
Ä ~orr·®( =t£Wt2(o£WHµW?£~®t?r
S
ÅoX2¸t~4stor®ÆCrt2~~dt
µ@ortt?ÁC£t2~~4M 2 (ω)dt
*M¹t*ort 4t?rtH·±¿?t2-s^s^t?NGp4tHv ,(4tH~=£r~c¼orts^s^t?4vW±rt?®jortor±
~ort?·±·
S
W·±rω
µEortH£t+ort£st+ortH~t¯r£±£~H¹ 6£rortHs^tµ ortjor®t+WW t?¸tHt?ÁC=4rt?NJWX^4~~»Är£mp·±tH4r~*¸t?}*±4t?tH~±r ^r=t?±tH~H¹
"!$#%&%')(*+!,-/.0%1%123!
{C}Cs^s^t}Gr=t?±tH~ WL~o£W=t£~·®Ut±4(~}Css^t?}%r=t?±tH~ W=~[s^s^t?N[¯r£m±£~H¹
¬ t(¶·±·Vs*WÆt£~tWort¯·±·±@¶±r v¶*r4=t?±tH~ *M~tHtrCW±¼Jr=tH£ÃÁ ,¾
4 ¨ Í65EÉ ¨@§ Ê87"9
G#! !"#
I
$&% #:+,.-/S
: #$ #! !"!# $ % 5"#M 2p
$%9"$ ,#
9
I( S ) = S ⇒ ∀ ω M 2p (I(ω)) = M 2p (ω)
4 ¨ Í65EÉ ¨@§ Ê'9 !%
M 2p
+/ # #! 2!I
+ #ω
O+/ +, L:L> ", $&%
M 2p
#27ω
9∀ ω M 2p (I( ω )) = M 2p ( ω ) ⇒ ( ∇ M 2p )( ω ) = 0
nportH~tGж+r=tHt2~J 4tort?±s^r·±}o£Ucort^UÁt2~ÅWEort^~}Ns^s^t±tH~W+~o£=tvt%
=t(¯4r£¼¼ortG±4tH~tH±j ortv~t~JEtH±£~J¶or®oh¿?t?^o£t% 44tH4~W[tH4o¼W[~
s^s^tH4%¯££m4£~?¹hnport£4XtH±tH~%Wt*rWvt2±rr?W·[o£@¶tH¸t?2¾G£?t^ort+±tH±£~%Wport
¿Ht?N~ÅWEort rtH4~ÅEorts^s^t?N¯r£±£~co£@¸tG =tHt?h¯4r£ºµLo£t?}¼sG£~c =t^ort2Æt2¼4
ort%~o£=tÃ~tH·ÃA*t?·±s^±£Utc·±~t=4~±¸tH~H¹
23 %1) 3
!CÆC±r p¯4!ort¿Ht?4~VWort rtH4!orts^s^tH4¯r£m±£~tH½Nr±t2~VrtH®~tWX%t?£~t~Ws»
r·±±r GºortH~tůr£m4£~HµN¶o£±o¶£·± =t¸t?}^N~·}^£~±r %ort?±±4tH W·£¯s W! ½N£U4UJ4¹
¬ t%oC£~ÅrtH~t?N¼t±t?Ns^torj+s^rrt%ortv t?£t?W·±¿HtHt?¸tH¼s^s^t?Nůr£m±£~Å
*~o£=tµr£~£ *~rort?®?W·Vo£Ws^r®?~H¹ м£W®r·®W2µ¶t%?jHrUt?·±}?s^rto£t%~rort?®?W·
o£s^4r±CtÂ?tH4~Wo£t(s4s^t?4¯r£±£~J¶ÃorÅ~Ws^r·±±r vortH~t££m4£~?¹
5AÉ ¨ª© + ©¨ Í Mª¦ ¬ tJ£~tt2W·»6¸WW·±rtHv~rortH®?·o£Ws^r®?~OHRÅ £~?J2²,JMC(tHrtH~t?4
±tHm4£W·¯rXm±X~?¹[tH·£~rortH®?·ro£Ws^r®?~EWtt?°£rtHVµ¯4E±4tH tH~
l ≥ 0
W£− l ≤ m ≤ l
µr N}L¾Y l m (θ, ϕ) =
√ 2 N l m P l m (cosθ) cos(mϕ)
¯40 < m ≤ l N l m P l 0 (cosθ)
¯m = 0
√ 2 N l m P l −m (cosθ) sin(mϕ)
¯4− l ≤ m < 0
¶ortHt
P l m
WtAo£tE4~~?±UtH,Vt? 4t?£rt =4·}Cr4s^±·±~)8HortEr4s*W·±±¿HU±c?£~4~N l m
Wt[~£oo£Uort%~rortH®?·Lo£s^4r±H~¯s or4rs*W·L~tJW¯rXm±X~p¯port%~HW·®Wprr£m2¾
< f, g >=
Z
kωk=1
f (ω)g(ω) dω
npor®~JtH~XXr~*orC4~±r £¾
N l m =
s 2l + 1 4π
(l − | m | )!
(l + | m | )!
¬ t-¶±··cX~tort-¯·±·U¶£ ¸4t?}f=@¶tH¯r·cr=tH} WG~rortH®?·o£Ws4r®?~H¾ WN}'~rort?®?W·
o£s^4r±ptH t?t
l
HW =t*t?Árt2~~tH- WUt2 C±£Ut^~}C~tHs £~£ jo£s^£±H~c~Ws^t(t? 4tHtW£jCtÂ?tH4~Jt?=tH££ ^4+ort(WU±
R
¾Y l m ◦ R = X
−l≤m 0 ≤l
D m,m
0
l (R)Y l m 0
*6 ,
ÅN} 4sG r±£U4 W~rortH®?·o£Ws^r®?~Gt? 4tHt·t2~~Go£W
l
? ort?t¯4t+ =t+tÁrtH~~t2±¼*UtHjC4±£Wt(~}~t?s £~£ ~£ort?±HW·Vo£Ws^r®?~W[tH t?t·±tH~~po£W
l
¶ÃorrÅ·N~~±¯s*U4V¹uCt?Â*?tH4~
D m,m
0
l (R)
HW t±t?N·±} =t^ W±rtH-£~±r tH?rtH£tG¯4sGr»·®Wt2HиUr®ÅWXrt2t?C =t? JH4 MX4±t2m·}*?s^rt2UHÅWs*Ws^C4orX£ RWrWo£W¡4¡@LM6¹
Í 5 §H©r§ Í'Í Í É § ªW§ Í ¦ ~Åt?°£rtH¼ N}( ½N£W± Jµ£o£t
2p −
s^4stH4ůr£»4W ^~o£W=t
S
®~pt?Árt2~~tH+4~?¾M 2p (ω) = Z
s∈S k s × ω k 2p d s
= Z
s ∈S k s k 2p sin 2p β ds
Ðor®~tÁrtH~~±!µ
β
®~ort%W£ ·±tc =t¶tHt?s
£ω
¹6rr£±
β 7→ sin k β
o£4~cWr 4r·®Wct?=tH£t?Xtβ
4r·}hW£hortHt?¯tvt2s^=N~t2~ÅN¿H£W· o£s^4r±H~ *¯6¹t¹o£Ws^r®?~
Y l m
¯4¶or®om = 0
,m¹AtH¯4s^±r ort*?·±?r·®U± ~orU¶J~o£UJ¶ort?
k
®~ptH¸t?Vµort%rtH4s=N~4+±~p°£rt4¹{Ct?±rk = 2p
µr¶t4 ¾sin 2p β =
p
X
l=0
S l p Y 2l 0 (β, .)
¶oV¾
S p l =
p (4l + 1)π 2 2l
2l
X
k=l
( − 1) k 2 2p+1 p!(2k)!(p + k − l)!
(2(p + k − l)+1)!(k − l)!k!(2l − k)!
nport-4tH~=£±r rt?±¸UW±f®~C ·±r =ttÁ=4~tHfort?tµ rjCt2~rW+rtH~t?4WC}
Âr·}¹
Vt
R s
Xt*+WU±4h¶or®o-s*£~
z
µVrr(¸t2m·4rz −
WÁ±~HµLs
¹3~±r ( ½4XU± ¯4U£ vort
Y 2l 0
¿H£·ºo£Ws^r®?~HµC¶t(o£2¸t^¾sin 2p β =
p
X
l=0
S p l 2l
X
m=−2l
D 2l 0,m (R s )Y 2l m ( ω )
Å£+°££W·±·±}L¾
M 2p (ω) =
p
X
l=0 2l
X
m=−2l
C 2l,m 2p Y 2l m (ω)
*M² ,£~±r
C 2l,m 2p = S l p
Z
s ∈S k s k 2p D 0,m 2l (R s ) d s
*"@ ,½N£W± ²r@¸t2~JoXU
M 2p
tH?s^=4~tH~Nj NrsG =tHW~rortH®?·oXWs4r®?~HµL£½N£W± @ W·±·±@¶J~*£~ rtH·±} 4s^rthort-t±t?4~?¹ nport-4~W%4s^r±r
M 2p
®~ortHt?¯t
(p + 1)(2p + 1)
~£4t^NtH W·®~ *rt*±4tH W·[=t?%tH¸t? 4rt?o£s^4r±µV£ht?
2p
,m¹hnpor®~%®~%sG£o ort2W=tH(oXW`ort·Ãt?£U±¸t*st?orr`WJ4s^r±r ¼ort+~HW·®Wr£JW
M 2p
~Jt?°£rt% N} ½N£W± J4µr¶o¼tH4o¼~rort?®?W·Vo£Ws^r®c £4~®~p¯r£±V¾or®~¶4r·®±£t?t2+t2½4£ts*N}t?¸WW·±£U4£~
M 2p
µr¶or®o~t?·A±~t?°£rtH4~p^~r?t±4t? 4·M¹ 6rrortHs^4t4µNrs^t?®?W·J4??r4} ±~*r·±} 4£tH£tH ¶ortHf4s^r±r ortC 2k,p m
?CtÂ^»?tH4~Hµ£W£+¶t(?r@¶<?s^rt =Wo
M 2p
W£Ã~p 44±t?4JW£·}N±HW·±·}*¯4s ½N£W±j²£¹
? "V ! "#%$f "!)(,-
Ð o£±~~t2m±!µA¶t£t2~t?NG4rv· 4Ãors ¯G®tH4¯}C£ -~}Ns^s^t±tH~GWÅh~o£W=t~t?tH 4~G
~£ ·±t%t?4Ã}4µL~J4r=4~tHortW·± 4ors rtH~t?NtH¼¼ortGrtÁCc~tH±¼¶ortHt%ortv~o£=t%±~
°£~ctH?s^=4~tHj±4+~r »Ä£W~H¹6£c ±¸t?~oXW=tµ=¶tv¶WNÅ+tt?s^rtGo£tvWÁ±~
X
WXort
(λ, α)
XWWs^tt?~JEort=t?N®W· ®~4st?±tH~?µLX~±r ort 4t?rtH·±¿?t2¼s4s^t?4¯r£m4£~?µ£o£tHÆ*ort(±~s^t±tH~¯rX 4£~o£t(4m£W·V~o£W=t4¹
ut?4·r~}Css^tt2~ *
λ = − 1
£α = π
,A¯s ~Xt2°X?~tµ4~±£t C}v4£~Xm±!µM 2p
·¶@}~o£~^t?NW·V~}Cs^s^t}4¹[ÀtH?£~tt?NW·V~}Cs^s^t±tH~W·®~^^£WtH½Nr±tWÁC®~HµC¶t
t2Uo£±~H~tűt2m·}*UortÅs^tWort2ÆC±r %ortortH?WX±£Utc~}Cs^s^t±tH~*ortc~oXW=t
~t?·A±h{CtHm±¼r¹²£¹
) (*%& /23 / !
~c¶t*~@¶´ {CtH± @X¹ort*UÁ®~±~s^t±tH~c¶or±o-·±t%~oXW=t ·± £··±}jr£o£W£ tH-W·®~
¿Ht?Go£tc rtH4W!ort t?£t?W·±¿HtH*t?¸tHs^s^tH4~Vor®~p~o£W=t¹ ¬ toN£~p W±+v~r=t?~t
ortHs N}+~·±¸C£ v¯2¾
∇ ( M 2p )(ω) = 0
Ðf°£~~t?Vµ¶tjtH~±s*Utj-CrsG =t?*Wc¸tH~v¶or®o tj·±4~t-ort¼£·~·±±£~Hµ
C}-t?°£r±r jo£t~£ort?t*WJtH±£~G~W±r ¯s `±?4~Wort2V¹Ð`t2o ?tµort¸UW·±rt
k ∇ ( M 2p )(ω) k 2
±~^tÁrWs^±rtH ± ~t?¸t?W·p±t2m4£~£ ?tH~^Wt~tH N} t?WÅort s^±rs*·E¸UW·±rt¯££º¹+w£·}ht2~¶o ~s^··Es±r±sGrs ¸WW·±rtH~(Wtt°££tH-tH£~¸tH·}4¹^nportCrsG =t?ºX4±4~E%·±CÆvW*t2o4tÅ~E¶t?·±·X4~ ortJCrsG =t?WL?tH~[%Æt?tHUtH4ot?o
·±t?¸tH·VWt?£~4£st?tH~Wort%W·± 4orsj¹
Ð^c~tH?£v~tH¶tp=t?¯sc~tHt?=tH~EtH~tH4[s^±r±s±¿HW±4
k ∇ ( M 2p )( ω ) k 2
µ~r¯s tHo Wo£t*HW£r±rWt2~¯4r£`rr ort^°£~%~tHV¹ 6r4cor®~(¶t^rtHtH-jtH¸UW·±£Wtvort
tH±¸UW±¸tH~
k ∇ ( M 2p ) k
µ4¶or®o*¶tJ%£~±r GW£·}N®?··±}vs^rtH*~tH4£t?t?¸WU¸t2~rort~rortH®?·No£Ws^r®?~AW·±r Ŷo ½N£U4v²r¹Anports^±rs^±¿HW±v?C¸t? tH~!±vůt?¶ ~t?£~
=tHHW£~t+~W±r =4~±£~vt¸t?}`·±4~t £·s^£s*r¹`npo£±~vs^tor o£4~%o£t£ r·t
4¸UWN t(o£W *&J-,orttH±¸UW±¸tH~ÅtG¸t?}t±t?N·±}¼4s^rt2W£ *6 ,JrWrr2Á±s*U4
®~^?NW±rt2 N ort¼HW·®r·®U4 ÅorthtH± Wort¼WÁ±~ =t?}4£ o£tjrt2®~± WÅort
HW·®r·®U4+Wort
C 2l,m 2p
Ct?Â*?tH4~?¹³År±r hor®~vrtH~~HµAsGr·Ã£·t+±£~£t2~%ort~s^t±tHm4 HW Xt¯rXº¹ ¬ t°£·Ãt?
ort?sr N}¼t2~s*W±r ort?±t?·®U±¸t®~W£?t¹ ¬ or±·t^rWor±r +±o£t?}j£tH¸t?4~Åortv°£~
~tH`¯4s s^±~~r ¼o£tt2W4m±4 Jjs^±r±sGrsjµ v¶Æ~¸tH}-¶tH·· ortrtH~t?N
?4tÁCH¹ УtHtHºµCs4s^t?4¯r£±£~WtJ¸t?}~s^CWoVµN£~o£=tH~o£2¸C±r (¶G®~4st?±tH~E¶o
¸tH}·±4~t}t?Jr%Lt?t?N UÁ®~ptc£WÅs^s^V¹
6±£··±}µX =tH?£~t%W·±·!s4s^t?4ůr£m4£~Ŷo£Ut?¸t?ort?±Å4tHHµrsG£~o£2¸tGWjt?ÁCt?sGrs
ortj±t2m± Jort¼UÁ±~vJort¼~}Cs^s^t±tH~vWÅortj~o£W=t4µE¶t?s^rt~£o ~t~v±t2m»
4£~¯%sG£·Ã£·ts4s^t?4%¯r£±£~ *t¹ £¹
M 4
µM 6
£M 8
,mµA rrGÆt?tH`r·±}hor4~t*¶or®o~sG£·ÃWrtH£~·}¿Ht?vort( 44±t?4W ··ºortH~t¯r£m4£~H¹
) (*%& /23 (*-)2 3 /(-%') (*!
Jt?°££rr ortv¿?t?W»Ð±t2mX~¯4Åortv ±t?NÅW[ortvs4s^t?4¯r£±£~Hµ=¶tv~±·±·rtHtHj
°££(ort£WWs^tt?~ºort4tH~=£±r ®~4s^t® WX~¯s*~?¹npor±~±~A£ttt?s±r®~±HW·±·}
C}~£}C±r ort~rort?±HW·o£s^£±ECt?Â*?tH4~VWorts^4stH4!¯rXm±X~VortHs*~tH·¸t2~?¹ ¬ to£@¸t
ort¯·±·U¶±r r=tHt2~?¾
4 ¨ Í65EÉ ¨@§ Ê&9 % "$I+,N#2 !:$ #! 2!
S z
:$ > +/
z = 0
-9< 9%2 >?$ ,%7 #2#-,+/!".5+/ !$ " $)4""# %$
+ "+
l + m
#NS :2;=:$ I >L.$ -,$N#!#$,$
z −
#! 2!"A+/ !$,"#2$ , !U+/(#-/. . #$&% +,($ , % "$/# 9∀ ω M 2p (ω) = M 2p (S z ω) ⇔ m ≡ 0(
$)>2) ⇒ C 2l,m 2p = 0
4 ¨ Í65EÉ ¨@§ Ê 9 % "$S+/N#U : $ "$ # ! :$ > +,
z
#?%I >V$ %?>Q.$ -/$N##2$,$2;=$ 9 9+/ $,"#2$ , Y-
∀ l ∀ m m 6 = 0 ⇒ C l m = 0
4 ¨ Í65EÉ ¨@§ Ê %9"$ S##% #!< +:$ LN+ :$ "$
R α
$ % L<
α
:$ 9>z
% 9>$, % "#A#-/+/!". +, !$ " .$) ",#
C l m
!% 9∀ l ∀ m C l m = cos(mα)C l m − sin(mα)C l −m
*6 ,E=tH}^HW* =tÅrt2vGo£tHÆúortJ¯r£±±~~tH·Ã»Ð~±s^·®WEorr 4oort4s^=4~Ã4
WU4£^(~}Cs^st?}G¶o^o£tÅ~s^tWÁ±~*¯6¹t¹AortÅH~t
λ = − 1
~Et°XrtH^±{tHm4*² ,m¹Ðor®~J?4~tcort(t2½4XU±+* =t(ortHÆtH¯4±~H¾
∀ l ∀ m ( − 1) l+m C l m = cos(mα)C l m − sin(mα)C l −m
*M ,nport2~tÅr=tHt2~WtJtH4~±·±}tH±¸tH^¯s ort¸t?}vt?Árt2~~±^ºortc~rort?®?W·Xo£Ws^r®p¯r£»
4£~AHRJ4 £~4 J2²/JM6¹
Àt?¯tvX~±r +ortH~t£4=t?±tH~Hµ=ort^s^s^tH4¯r£± sGX~( =t^tÁrtH~~tHh±`C4r£Wt
~}~t?s ¶ort?t^ort
z
UÁ®~%±£?±t2~(¶o ortrtH¸C4£~·±}h¯r£ ?WX±£UtUÁ®~?¹jnpor±~%®~%=t?»¯4s^tH£~±r +ort^W±¼¯4sG£·±± ½N£W±`¹GnportH ort2ÆC±r ¯4cr=tHt2~c²+WXU@±~
±¸C±·=£U¸C±t2*oXUJ~4st·±t?W£?tÅ®~??t?tHorttH½N£W·±±tH~H¹53~±r £4XtH}%®~ps4t
~r ·t4¾J?Ct±t?N~W[ortG¯r£±-t%°£~ctÁrWs^±rtH¼ C}jt?WrtHtH4~±r
m
¹A6£λ = 1
¯4£~£t4µ¶ortH+ort°£~£¿?tH^¸UW·±rtW
C l m
®~p¯r£ºµ ½N£U4¼v®~~·±¸tH C}L¾tan mα
2 = C l −m C l m
M¹t¹
α = 2 m arctan
C l −m C l m
+ kπ
m
ort? W·±·Eortt?s*r±r t±t?N~vWtort2Æt2`¶o ort+ W±rtH ¸UW·±rt2~%W
α
¹hÄorttH~£4~~tH~Hµºort?
α
®~ortWr 4·t^pW`tÁ®~£ jW±»Ð~}Cs^s^t}j¯(orts^s^t?N(¯r£m4V¹+¸tH}~s^±·±pr?tH~~®~£~t2*~t2Wo¯4
α
¶ort?λ = − 1
¹nportt?4Å4·tH£tv£~t2¶ort? ortHÆC£ ¯r=tHt2~²£µ @jWX-+? =t^?£~±rt?tH~
^¶@} rtt2mr Wrr@ÁC±s*Ut~}Css^t?t2~pj tH~H¹ ¬ t%¶·±·!~orU¶:jort%t2~£·Ã~~tH±
o£UÅ~}Cs^s^t±tH~HWXt?t2+ =t%ttHtH4=t?r £WtHjrUrµr~£oj~~?rrtH+s^tH·±~H¹
) (* (2! !
nport^4£±£~t?ÁCmtH¼¯4s 4=t?±tH~2JW£ WtGrt2tH~~}j?£rÃ4£~r·±}4¹(n@¸®
·±~tÅ=4~øt2~?µ4ortc±t2m4£~£*WU±W£ ·±tH~E4 rt2^¯4s o£tÅs^s^tH4¯r£m±£~sG£~
ort?t¯t( =t%¸t?°£tH4ortG~o£=t(~t?·¹ ¬ tv^or®~J£~±r #! 2! . #: X~r±tH C}
ort¶4Æ^W LW rr~ÆC}vtp·M¹ HPJH44NMĹVt?
S
£R
=tŶGt2~~t?·±·±Wt2~oXW=tH~H¹Vt?V S
W£
V R
=tort(s^tH~o¸tH±?tH~pW
S
£R
¹ ¬ t%t°Xrtort . #:d M
=t¶t?tH
S
£R
N}L¾d M ( S , R ) = max
p∈V S
(min q∈R k p − q k )
*Ä¢ ,nport
#! !" N#!:
d A ( S )
W~o£W=tS
¶ot2~=t2mJ~}Ns^s^t}A
±~Jort?-t°£rt2C}=¾
d A ( S ) = max(d M ( S , A S ), d M (A S , S ))
Ä~orr·® =tcrWtH*o£Uo£±~pt?°£r±+®~%=tHtH4¯s o£WVort
2 #>L$ ># 9.
~Xtµ
± ½N£W± ¢¾%rWvW·±·E=±4~(
S
tX~®t?tH- £Gr·±}horts^tH~o ¸t?®t2~?µ!¶o£t?tH~(··=4N~W
R
Wt£~t2º¹ RJU¶tH¸t?2µ2 =t2?W£~tS
±~=4·}Cort2·Mµd A ( S ) = 0
~±··Cs^r·±±tH~!o£UA S = S
¹us^rr
d A
®~p?4~·±}µC r¯r£Wt?·±}*¶tr·±}*=t?¯s Ãp¯G¯t?¶<or4®tH~W
A
¶or®otortj?WX±£Ut2~v¶t¯££ Wvo£t+£tH¸N±X~v~t? Jortj· 4Ãorsj¹ npo£±~^4s£W± ±~
sG£o ort2W=t?2µ[± £±?r·±Hµ o£ 4s^r±r h¯r·±·~}Cs^st?} tH~r HW(W¿Ho£r t?^·6¹
¡¡@LM6µ¯pv~±t?4pCrsG =t?pW±t2m±X~Evt2o*ortcrtH®~4*!rp~}Cs^s^t}*t?t2m±
· 4Ãorsj¹
-%'
nporth¶o£·±t¼rt2~~*±~·±·X~WtHf 6A± rtr¹ {Nr ¯4s ort 4XW·4 Ct2m
(a)
µports^s^tH4¯r£m4£~WÅ4tH~
4, 6
W£8
Wt+?s^rt2 *t¹ £¹M 8
(b)
,¹ npo£t+ rtH4vortH~ts^4stH4~®~portH¼s^rtHjWXW·±}4±HW·±·±}
(c)
µ££+£~tH+¯p°££rr ^ort%±t2m±X~pWort s^±rs*£¹:nporthr°£·tHt2f~tW(±t2m4£~N£~7
±t2m4£~?µps^r `¶or®of4r·}3
t?s^s^¼t?ÁNt?s**W
M 4
µM 6
£M 8
¹npor®~~tcW3
±t2m±X~*D 1
µ
D 2
W£
D 3
,Å?4W±£~
ortGWÁtH~Aortv~}Cs^s^t±tH~JW ortv~o£W=t4¹
D 1
®~o£tGWÁC®~EU»M¯4·±¼~}Cs^s^t}4µ£¶or±o¼®~ort
?s^=4~Ã4+Wortж^t?s*W±r±r s^»Ä~}Cs^st?±tH~W WÁtH~
D 2
W£
D 3
¹
nporttÁrWs^r·±tvWEort^?r =tµV~orU¶ 6A 4rt Jv·±·±£~Wt2~Åortt?ÁCm4hWU±£~£
s^±»Ä~}Cs^s^t±tH~?¹, EÁXtH±s^t?N~co£@¸t~or@¶ho£U4rcs^to£h°££r~··Aort
48
~}Cs^st?±tH~¶o£WtH¸t?ort%XUt~}C~tHs ort%r =t(®~p4± ±£W·±}*tÁrtH~~t2V¹
M 8
D 2
D 1
D 3 (b)
k∇ M 8 k 2
(c) (a)
6A± rtcr¾ [ÁC4m±W~}Cs^st?t2~¯pv~£ ·±t~o£Xt4¹[{NW±r G¯sÇortc± ±£W·=~oXW=t
(a)
µ4t?rt?W·±±¿?tH`s^s^t?N~
(b)
W£`ort?±v 44±t?4~(c)
Wts^rrtHV¹-npo£t+~tvortHtÁCt?s*±tHm4`44X~cortUÁtH~o£t~}Cs^s^t±tH~(Wort~o£W=t4µt?£±tH U%± oNH¹ RJt?tµ =Wo
s^±»Ä~}Cs^s^t±tH~Ao£@¸t =tHt?^¯r£*4~[¶t?·±·X~[ortU»M¯4·±WW±£·r~}Cs^s^t}4¹
Wtpo£UEort
4± ±£W·º~o£W=t®~prtHÃort?Å4N¸t?ÁrJ~W»Ä~o£=tHº¹
! /! !
Å·Ãorr 4ohÃc¶Æ~pW±·}¶t?·±·6µXortW·± ors rtH~t?NtH¼¼or®~~tHm±¼o£4~ortv®~¸U4W t
o£Uvs^s^t?N%¯rXm±X~Gt·±s^ÃtH ±`¯tH½Nrt?£?}µ £ oC£~Gs*2} rWvHWrt*tHrr 4o`±¯»
s*U4 W =4co£t*~oXW=t¹npor®~±~(~=tH®··±}jrt¯rt2W·}N»Ð~}Cs^s^t®G?s^r·±tÁ-~o£=tH~~£o
4~portGrt%£t2~tH4t2jU6A 4rt%²£µ£¶o£t?t%*¸tH±HW·!s^4»Ð~}Cs^st?}¶±··s^4~År XW r·±} =t
t?tHt2+W·±·£orts^s^t?N~HµCWX*s*2}^rW =tJ°X·Ãt?tH*4 C}ortc~}Cs^st?}s^tH4~rtJ =t2?WX~t
%Lt?t?£t2~??rcU¸t?}j~s^·±·A~?·tG =t?жtHt?hortv¶o£t?t?·®~H¹npor®~s*2}j =t?£~±rt?t2hWh±»
t?tH~±r G¯t2UrtW!orts^to£¶ortHrr2Á±s*Utc~}Css^t?t2~pWtc~tHWortH*¯4H¹wÅo£t?¶±~tµ
or±~®~J·±s^ÃU±4Wort(s^to£º¹
Ï t?U¸t?HµNort
M 2p
¯r£±£~J =t?±r ± 4rs^t®=·±}N£s^±·®~+ort%~rortHtµortH}o£@¸ts*UÁ±sGrs CrsG =t?^W~±tÁCt?s*tH=t?£±r
p
¾*ort+·®W tHp
®~?µ[o£t+s^tM 2p
±~ r·tvj?WrrtGort^¯4s*W±~}Css^t?}µº6¹t4¹%oX2¸t^W-tÁCtHsGrs ±ort*tH±
~%WÁ±~H¹ÀG =tHHW£~t*··s4s^t?4%¯r£±£~%sv£~Go£@¸tjNr·±· rtH4(± or®~GtH±
*M??±r *+E=tH}h ,µ=ortH~tvt?ÁCt?s* =t2s^tvr4»Ä~®mctÁCt?s*¯~s*W·±·A¸U·rt2~Å
p
µ£
M 2p
±~G¯4t2`- =t+?£~4v4 ~r »Ärs*W± WJr4 N£··s^tH£~±!¹ npor®~G®~v¶o£Uo£r=t?£~t¹ £¹A¯4port%?r =tµr±j¶or±ojH~t