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ç®ãQã¨ãã¦ãé ç¹ã®éåã|Q|0, ã¢ãã¼ï¼æå辺ï¼ã®éåã|Q|1ã¨ãã¾ããs, t:|Q|1â|Q|0 ãååã¨ãã¦ãQ = (|Q|0, |Q|1, s, t) ãç®ã§ããæºããã¹ãå ¬çï¼æ¡ä»¶ï¼ã¯ç¹ã«ããã¾ããã
ä¸è¨ã®(|Q|0, |Q|1, s, t)ã«å ãã¦ãåå i:|Q|0â|Q|1 ããã£ã¦æ¬¡ãæºããã¨ãã(|Q|0, |Q|1, s, t, i)ãåå°çç®ï¼reflexive quiverï¼ã¨å¼ã³ã¾ãã
- i;s = id|Q|0
- i;t = id|Q|0
åå°çç®ã¯ãåããçµåï¼compositionï¼ãé¤ããæ§é ã«ãªãã¾ããaâ|Q|0ã«å¯¾ããi(a)ã¯æçå°ã«ç¸å½ãã¾ãããåå°çãã®ç±æ¥ã¯ãåå¤é¢ä¿ãªã©ã®åå°å¾ã«å¤å°ä¼¼ã¦ãããã§ãããè¨èãæ°ã«ããå¿ è¦ã¯ããã¾ããã
åã®å ´åã¨åæ§ã«ãa, bâ|Q|0ã«å¯¾ããã¢ãã¼ã»ãããQ(a, b)ã¨æ¸ãã¾ããfâQ(a, b) ã f:aâb in Q ã¨ãæ¸ãã¾ãã
åå°çç®ã®å¥ãªå®å¼å
Aãéåã¨ãã¦ãæ§é (A, â, ◁, E)ãèãã¾ããããã§ã
- âã¯Aä¸ã®äºé é¢ä¿
- ◁ãAä¸ã®äºé é¢ä¿
- Eã¯Aã®é¨åéåã
âã¯å ±ç«¯é¢ä¿*1ã◁ã¯é£æ¥é¢ä¿ã¨å¼ã³ã¾ããfâg ã¯ãfã¨gã¯å ±ç«¯ããf◁gã¯ãfã¯gã«ï¼ãã®é ã§ï¼é£æ¥ãã¦ãããã¨èªã¿ã¾ãã
次ã®å ¬çãä»®å®ãã¾ãã
- âã¯Aä¸ã®åå¤é¢ä¿
- fâf', gâg', f◁g ãªãã°ãf'◁g'
- xâE ãªãã°ãx◁x ï¼èªåã¨é£æ¥ãã¦ããï¼
- x, yâE, xây ãªãã°ã x = y
- ä»»æã®fã«å¯¾ãã¦ãx◁f ã¨ãªã xâE ãããã
- ä»»æã®fã«å¯¾ãã¦ãf◁y ã¨ãªã yâE ãããã
ããã¯ãåå°çç®ã®å¥å®ç¾©ã«ãªãã¾ãã
ä¸ãããã(A, â, ◁, E)ã«å¯¾ãã¦ã(|Q|0, |Q|1, s, t, i)ã次ã®ããã«å®ç¾©ãã¾ãã
- |Q|0 := E
- |Q|1 := A
- s(f) := εx.(x◁f ã㤠xâE)
- t(f) := εx.(f◁y ã㤠yâE)
- i:|Q|0â|Q|1ã¯ãEâA ã®å å«åãè¾¼ã¿ã
s, tã®å®ç¾©ã«ä½¿ã£ã¦ãã εx.(â¦) ã¯ããâ¦ã§ãããããªxãã¨èªã¿ã¾ãã詳ããã¯ãã¤ãã·ãã³è¨ç®ã£ã¦ãªãã§ãããï¼ ãããªããã§ãããããè¦ã¦ãã ãããsã¨tãååã¨ãã¦well-definedãªãã¨ã¯ãå ¬çããããåºã¾ããi;s = id, i;t = id ãå®ç¾©ããåºã¾ãã
(|Q|0, |Q|1, s, t, i)ãã(A, â, ◁, E)ãä½ãã«ã¯ã
- A := |Q|1
- fâg :â s(f) = s(g) ã㤠t(f) = t(g)
- f◁g :â t(f) = s(g)
- E := i(|Q|0) ï¼iã«ããåéåï¼ã
(A, â, ◁, E)ã«é¢ããå ¬çãç°¡åã«ç¢ºèªã§ãã¾ãã
ååå°çç®ã¨æ¦åå°çç®
åå°çç®ã¨åãæ§é (A, â, ◁, E) ã§ãå ¬çãå¼±ãããã®ãèãã¾ãã
- âã¯Aä¸ã®åå¤é¢ä¿
- fâf', gâg', f◁g ãªãã°ãf'◁g'
- xâE ãªãã°ãx◁x ï¼èªåã¨é£æ¥ãã¦ããï¼
- x, yâE, xây ãªãã°ã x = y
ã¢ãã¼fã®ä¸¡ç«¯ã«Eã«å±ããèªå·±é£æ¥ã¢ãã¼ã決ã¾ããã¨ãè¦æ±ãã¦ãã¾ãããåã§è¨ãã°ãæçå°ã®åå¨ãè¦æ±ããªããã¨ã«ç¸å½ãã¾ããå¼±ããå ¬çãæºããæ§é ãååå°çç®ï¼semi-reflexive quiverï¼ã¨å¼ã¶ãã¨ã«ãã¾ããååå°çç®ã§ã¯ãEã空ã«ãªããã¨ã許ããã¾ãã
(A, â, ◁, E)ãåå°çç®ãªãããã¡ããããã¯ååå°çç®ã§ãããã¾ããAãä»»æã®éåã¨ãã¦ãAã«å¯¾ãã¦ã(A, â, ◁, E) ã次ã®ããã«å®ç¾©ããã¨ååå°çç®ã«ãªãã¾ãã
- a, bâA ãªããa, bãä½ã§ã aâb
- ã©ã㪠a, bâA ã§ãã a◁b ã¨ã¯ãªããªãã
- Eã¯ç©ºéå
ãã¦ããããã nâ§0 ã«å¯¾ãã¦n-æ¦åå°çç®ï¼n-almost reflexive quiverï¼ã¨ãããã®ãå®ç¾©ãã¾ããn-æ¦åå°çç®ã¯ã次ã®æ§æç´ ãæã¡ã¾ãã
- 0⦠j â¦n ã«å¯¾ãã¦éå |Q|j
- |Q|jä¸ã®ååå°çç®æ§é (|Q|j, âj, ◁j, Ej)ã
- 0⦠j â¦(n - 1) ã«å¯¾ãã¦åå sj, tj:|Q|j+1â|Q|j
- 0⦠j â¦(n - 1) ã«å¯¾ãã¦åå ij:|Q|jâ|Q|j+1
sj, tj, ijã¯æ¬¡ã®é¢ä¿ãæºããã¾ãã
- sj;tj-1 = tj;tj-1
- tj;sj-1 = sj;sj-1
- ij;sj = id
- ij;tj = id
ããã«æ¬¡ãæºããã¨ãã¾ãã
- jâ§1 ãªãã°ã(|Q|j, âj, ◁j, Ej) ã¯åå°çç®ã§ãããsj-1, tj-1, ij-1 ã«ãã£ã¦ä½ãããåå°çç®æ§é ã¨åãã§ããã
æå¾ã®æ¡ä»¶ã詳ããè¨ãã¨ï¼
- fâjg â sj-1(f) = sj-1(f) ã㤠tj-1(f) = tj-1(f)
- f◁jg â tj-1(f) = sj-1(g)
- Ej = ij-1(|Q|j-1)
(|Q|0, â0, ◁0, E0) ã ããä¾å¤çã§ãåå°çç®ã§ãããã¨ã¯ä¿è¨¼ããã¾ããã
ä»ã¾ã§ã®å®ç¾©å ã§åºã¦ããä¸éå¤nããªãã¦ãä»»æã®jâ§0ã«å¯¾ãã¦ä¸è¨ã®æ§é ãå®ç¾©ããã¦ããã¨ãã¯ãâ-æ¦åå°çç®ã¨å¼ã³ã¾ãã
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é¨åã§ãã|Q|0ä¸ã«ååå°çç®æ§é (|Q|0, â0, ◁0, E0) ãè¦æ±ãã¦ã¾ãããå®éã«å¿
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Cãn-åã¨ãã¾ããn-åã®å®ç¾©ã¯è²ã ããã¾ãããã¨ãããã次ã®ãã¨ãä»®å®ãã¾ãã
- 0⦠k â¦n ã«å¯¾ãã¦ãCã®k-å°ï¼k-ã»ã«ãk-ã¢ãã¼ï¼ã®éåã決ã¾ã£ã¦ãããCã®k-å°ã®éåã|C|kã¨ãããç¹ã«ã|C| = |C|0ã
- aâ|C|kï¼0ï¼ k â¦nï¼ãªããdom(a), cod(a)â|C|k-1 ã§ããã
- aâ|C|kï¼0⦠k ï¼nï¼ãªããidaâ|C|k+1 ã§ããã
ããã¯ãn-åCãn-æ¦åå°çç®ã決ãããã¨ã示ãã¦ãã¾ãããããã¯ãn-åã®å°æ§é ãn-æ¦åå°çç®ã§ããã¨ãè¨ãã¾ãã
n-åCã決ããn-æ¦åå°çç®ãããå°ãããããªã¨è¨è¿°ãã¦ããã¾ãããï¼ |C|kä¸ã§å®ç¾©ãããdom, cod㯠dom(k-1), dom(k-1):|C|kâ|C|k-1 ã¨æ¸ããã¨ã«ãã¾ããä¸ä»ãæ·»åã®çªå·ã(k - 1)ã§ããç¹ã«æ³¨æãã¦ãã ããã|C|kä¸ã§å®ç¾©ãããidã¯ãid(k):|C|kâ|C|k+1 ã¨ãã¾ãã
s, t, iã®ä»£ããã«dom, cod, idã使ãã®ã§ãä»å¾ã¯æåiãçªå·ã«ä½¿ããã¨ã許ãã¾ãã
念ã®ããã«ãdom, cod, idãæºããçå¼ãå度æ¸ãã¦ããã¨ï¼
- dom(i);cod(i-1) = cod(i);cod(i-1)
- cod(i);dom(i-1) = dom(i);dom(i-1)
- id(i);dom(i) = Id|C|i
- id(i);cod(i) = Id|C|i
ããã§ãid(i)ã¯ç®ã®æ§é ãå®ç¾©ããååã§ãId|C|iã¯âi-å°ã®éå|C|iâã®ä¸ã®æçååã§ãã
n-åCã®å¯¾è±¡ã®éå|C|0ã¯åãªãéåãªã®ã§ã(|C|0, â0, ◁0, E0) ã¯èªæãªæ¹æ³ã§å®ç¾©ãã¦ããã¾ããã¤ã¾ãã
- A, Bâ|C|0 ãªãã°ãAâBã
- A, Bâ|C|0 ãªãã°ãA◁B ã§ã¯ãªãã
0ï¼ i â¦n ã«å¯¾ãã(|C|i, âi, ◁i, Ei) ã¯ãdom, cod, idããèªåçã«æ±ºã¾ãã¾ãã
n-åCãã決ã¾ãn-æ¦åå°çç®ãåãè¨å·Cã§è¡¨ãã¾ããn-æ¦åå°çç®Cã¯ãk-å°ã®éåï¼k = 0, 1, ..., nï¼ã¨ã3Ãnåã®ååããæ§æããã¾ãã
n-æ¦åå°çç®Cã«å¯¾ãã¦ããã®1-ã·ããã¯ã|C|0ãæ¨ã¦ã¦ãçªå·ãä»ãç´ãã(n - 1)-æ¦åå°çç®ã§ããCã®1-ã·ãããC[1]ã¨æ¸ãã¦ãã·ããããdom, cod, idã¯ãdom[1], cod[1], id[1]ã¨ãã¾ãã
- 0⦠i ⦠(n -1) ã«å¯¾ãã¦ã(C[1])i = Ci+1
- 0⦠i ⦠(n -1) ã«å¯¾ãã¦ã(dom[1])(i) = dom(i+1)ã(cod[1])(i) = cod(i+1)ã(id[1])i = id(i+1)ã
ãã®å®ç¾©ã§ãC[1]ã¯n-æ¦åå°çç®ã«ãªãã¾ãã|C[1]|0 = |C|1ä¸ã®(â, ◁, E)æ§é ã¯åå°çç®ã«ãªãã¾ãããåå°çç®ã¯ååå°çç®ãªã®ã§åé¡ããã¾ããã
Cãn-æ¦åå°çç®ã®ã¨ãã0⦠k â¦n ã«å¯¾ãã¦k-ã·ããã次ã®ããã«å®ç¾©ã§ãã¾ãã
- C[0] := C
- C[k] := (C[k-1])[1]
C[k]ã¯(n - k)-æ¦åå°çç®ã«ãªãã¾ããC[k]ããCã®k次å æªæºã®ã»ã«ãæ¨ã¦ãæ§é ã§ãã
å ±ç«¯å¯¾ã¨ãã ç®
é常ã®åDã«ããã¦ãA, Bâ|D| ã«å¯¾ãããã ã»ããD(A, B)ã¯å¤§å¤ã«ä¾¿å©ãªæ¦å¿µã§ããé«æ¬¡åã«å¯¾ãã¦ããã ã»ãããå®ç¾©ãã¾ãããã
Cã¯n-åã ã¨ãã¦ã対å¿ããn-æ¦åå°çç®ãåãCã§è¡¨ãã¾ãã0⦠k ï¼n ã¨ãã¦ãa, bâ|C|k ã¨ãã¾ããåã次å ï¼kï¼ã®å°ã¯å ±ç«¯ãã©ãããå¤å®ã§ãã¾ããaâkbã®ã¨ãã(a, b)ãk-å ±ç«¯å¯¾ã¨å¼ã³ã¾ãã
- k = 0 ã®ã¨ãã¯ãaâ0b ã¯|C|0ä¸ã®é¢ä¿ã¨ãã¦æ±ºã¾ãã
- k ï¼ 0 ã®ã¨ãã¯ãaâkb 㯠dom(k-1)(a) = dom(k-1)(b) ã㤠cod(k-1)(a) = cod(k-1)(b) ã®ãã¨ã
a, bãk-å ±ç«¯å¯¾ã®ã¨ããC(a, b)ãå®ç¾©ã§ãã¾ããC(a, b)ã¯ã(n - k - 1)-æ¦åå°çç®ã«ãªãã®ã§ãaããbã¸ã®ãã ç®ã¨å¼ã³ã¾ããC(a, b)ã¯é«æ¬¡ç®ãªã®ã§ã(n - k)åã®éå |C(a, b)|0, ..., |C(a, b)|n-k-1 ã¨å次å ã®dom, cod, idã§æ§æããã¾ãããããã®æ§æç´ ãå®ç¾©ãã¦ããã¾ãã
æºåã¨ãã¦ãXâ|C|jï¼0⦠j ï¼nï¼ã«å¯¾ã㦠X#â|C|j+1 ãå®ç¾©ãã¾ãã
- X# = {aâ|C|j+1 | dom(j)(a)âX ã㤠cod(j)(a)âX }
(X#)# = X## = X#2, ((X#)#)# = X### = X#3 ã®ããã«ãæ¸ãã¾ãã
ãã¦ãC(a, b)ã®å®ç¾©ã§ããC(a, b)ã«ä»éããdom, cod, idãdom', cod', id' ã¨ãã¾ãï¼ãã以ä¸ã®æ·»åã¯ç ©éãªã®ã§ï¼ã
- |C(a, b)|0 = {xâ|C|j+1 | dom(j)(x) = a ã㤠cod(j)(x) = b}
- |C(a, b)|i := (|C(a, b)|0)#i
- dom'(i) := (dom(k+i)ã®|C(a, b)|i+1ã¸ã®å¶é), cod'(i) := (cod(k+i)ã®|C(a, b)|i+1ã¸ã®å¶é), id'(i) := (id(k+i)ã®|C(a, b)|iã¸ã®å¶é)ã
以ä¸ã«ãããC(a, b)ã¯ã(n - k - 1)-æ¦åå°çç®ã«ãªãã¾ãã
å®ä¾ï¼å°ããåã®å
n = 2, C = Cat ã®å ´åãèãã¦ã¿ã¾ãã
- |Cat|0 = (ãã¹ã¦ã®ï¼å°ããï¼åã®éå)
- |Cat|1 = (ãã¹ã¦ã®é¢æã®éå)
- |Cat|2 = (ãã¹ã¦ã®èªç¶å¤æã®éå)
- dom(0), cod(0), id(0) ã¯ãé¢æã®dom, cod, id
- dom(1), cod(1), id(1) ã¯ãèªç¶å¤æã®dom, cod, id
ãã ç®ã¯äºç¨®é¡èãããã¨ãã§ãã¾ããAâ0B ã«å¯¾ããCat(A, B)ã¨ãFâ1G ã«å¯¾ããCat(F, G)ã§ãã
A, B ãå°ããåã¨ãã¦ã(2 - 0 - 1)-æ¦åå°çç®Cat(A, B)ãå®ç¾©ãã¾ãããï¼ Aâ0B ã¯ç¡æ¡ä»¶ã«æç«ããã®ã§ã1-æ¦åå°çç®Cat(A, B)ãå®ç¾©ã§ãã¾ãã
- |Cat(A, B)|0 = {Fâ|Cat|1 | dom(0)(F) = A ã㤠cod(0)(F) = B}
- |Cat(A, B)|1 = (|Cat(A, B)|0)# = {αâ|Cat|2 | dom(1)(α), cod(1)(α)â|Cat(A, B)|0 }
F, G ãé¢æã¨ãã¦ã(2 - 1 - 1)-æ¦åå°çç®Cat(F, F)ãå®ç¾©ãã¾ãããï¼ Fâ1G ãªãã°ã0-æ¦åå°çç®Cat(F, G)ãå®ç¾©ã§ãã¾ãã
- |Cat(F, G)|0 = {αâ|Cat|2 | dom(1)(α) = F ã㤠cod(1)(α) = G}
2種ã®ãã ç®ã®å¯¾è±¡éåï¼0-å°ã®éåï¼ãç°¡ç¥åããè¨æ³ã§æ¸ãã°ï¼
- |Cat(A, B)|0 = Functor(A, B)
- |Cat(F, G)|0 = NatTran(F, G)
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n-æ¦åå°çç®ã®ããã ã®æºååå°ãå®ç¾©ããã°ãn-æ¦åå°çç®ã®ån-AReQãæ§æã§ãã¾ããk-ã·ããã¯ã(-)[k]:n-AReQâ(n-k-1)-AReQ ã¨ããé¢æã¨ãªãã¾ããã¾ããn-æ¦åå°çç®ãâ-æ¦åå°çç®ã«æ¡å¼µããé¢æ n-AReQââ-AReQ ãå®ç¾©ã§ãã¾ãã
n-æ¦åå°çç®ã®æ¦å¿µã«åºãã¦ãn-åï¼é«æ¬¡åï¼ã«é¢ããè¨è¿°æ³ãããå°ãæ´çã§ããããããªãããã¨èãã¦ãã¾ãã
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