Theorem fprodfac 12407

Description: Factorial using product notation. (Contributed by Scott Fenton, 15-Dec-2017.)

Assertion

Ref	Expression
fprodfac	|- ( A e. NN0 -> ( ! ` A ) = prod_ k e. ( 1 ... A ) k )

Distinct variable group:   A, k

Proof of Theorem fprodfac

Dummy variables w x are mutually distinct and distinct from all other variables.

Step	Hyp	Ref	Expression
1		fveq2 5698	. . 3 |- ( w = 0 -> ( ! ` w ) = ( ! ` 0 ) )
2		oveq2 6096	. . . 4 |- ( w = 0 -> ( 1 ... w ) = ( 1 ... 0 ) )
3	2	prodeq1d 12356	. . 3 |- ( w = 0 -> prod_ k e. ( 1 ... w ) k = prod_ k e. ( 1 ... 0 ) k )
4	1, 3	eqeq12d 2253	. 2 |- ( w = 0 -> ( ( ! ` w ) = prod_ k e. ( 1 ... w ) k <-> ( ! ` 0 ) = prod_ k e. ( 1 ... 0 ) k ) )
5		fveq2 5698	. . 3 |- ( w = x -> ( ! ` w ) = ( ! ` x ) )
6		oveq2 6096	. . . 4 |- ( w = x -> ( 1 ... w ) = ( 1 ... x ) )
7	6	prodeq1d 12356	. . 3 |- ( w = x -> prod_ k e. ( 1 ... w ) k = prod_ k e. ( 1 ... x ) k )
8	5, 7	eqeq12d 2253	. 2 |- ( w = x -> ( ( ! ` w ) = prod_ k e. ( 1 ... w ) k <-> ( ! ` x ) = prod_ k e. ( 1 ... x ) k ) )
9		fveq2 5698	. . 3 |- ( w = ( x + 1 ) -> ( ! ` w ) = ( ! ` ( x + 1 ) ) )
10		oveq2 6096	. . . 4 |- ( w = ( x + 1 ) -> ( 1 ... w ) = ( 1 ... ( x + 1 ) ) )
11	10	prodeq1d 12356	. . 3 |- ( w = ( x + 1 ) -> prod_ k e. ( 1 ... w ) k = prod_ k e. ( 1 ... ( x + 1 ) ) k )
12	9, 11	eqeq12d 2253	. 2 |- ( w = ( x + 1 ) -> ( ( ! ` w ) = prod_ k e. ( 1 ... w ) k <-> ( ! ` ( x + 1 ) ) = prod_ k e. ( 1 ... ( x + 1 ) ) k ) )
13		fveq2 5698	. . 3 |- ( w = A -> ( ! ` w ) = ( ! ` A ) )
14		oveq2 6096	. . . 4 |- ( w = A -> ( 1 ... w ) = ( 1 ... A ) )
15	14	prodeq1d 12356	. . 3 |- ( w = A -> prod_ k e. ( 1 ... w ) k = prod_ k e. ( 1 ... A ) k )
16	13, 15	eqeq12d 2253	. 2 |- ( w = A -> ( ( ! ` w ) = prod_ k e. ( 1 ... w ) k <-> ( ! ` A ) = prod_ k e. ( 1 ... A ) k ) )
17		prod0 12377	. . 3 |- prod_ k e. (/) k = 1
18		fz10 10467	. . . 4 |- ( 1 ... 0 ) = (/)
19	18	prodeq1i 12353	. . 3 |- prod_ k e. ( 1 ... 0 ) k = prod_ k e. (/) k
20		fac0 11188	. . 3 |- ( ! ` 0 ) = 1
21	17, 19, 20	3eqtr4ri 2270	. 2 |- ( ! ` 0 ) = prod_ k e. ( 1 ... 0 ) k
22		elnn0 9576	. . 3 |- ( x e. NN0 <-> ( x e. NN \/ x = 0 ) )
23		simpr 110	. . . . . . 7 |- ( ( x e. NN /\ ( ! ` x ) = prod_ k e. ( 1 ... x ) k ) -> ( ! ` x ) = prod_ k e. ( 1 ... x ) k )
24	23	oveq1d 6103	. . . . . 6 |- ( ( x e. NN /\ ( ! ` x ) = prod_ k e. ( 1 ... x ) k ) -> ( ( ! ` x ) x. ( x + 1 ) ) = ( prod_ k e. ( 1 ... x ) k x. ( x + 1 ) ) )
25		nnnn0 9581	. . . . . . . . 9 |- ( x e. NN -> x e. NN0 )
26		facp1 11190	. . . . . . . . 9 |- ( x e. NN0 -> ( ! ` ( x + 1 ) ) = ( ( ! ` x ) x. ( x + 1 ) ) )
27	25, 26	syl 14	. . . . . . . 8 |- ( x e. NN -> ( ! ` ( x + 1 ) ) = ( ( ! ` x ) x. ( x + 1 ) ) )
28		elnnuz 9975	. . . . . . . . . 10 |- ( x e. NN <-> x e. ( ZZ>= ` 1 ) )
29	28	biimpi 120	. . . . . . . . 9 |- ( x e. NN -> x e. ( ZZ>= ` 1 ) )
30		elfzelz 10445	. . . . . . . . . . 11 |- ( k e. ( 1 ... ( x + 1 ) ) -> k e. ZZ )
31	30	zcnd 9780	. . . . . . . . . 10 |- ( k e. ( 1 ... ( x + 1 ) ) -> k e. CC )
32	31	adantl 277	. . . . . . . . 9 |- ( ( x e. NN /\ k e. ( 1 ... ( x + 1 ) ) ) -> k e. CC )
33		id 19	. . . . . . . . 9 |- ( k = ( x + 1 ) -> k = ( x + 1 ) )
34	29, 32, 33	fprodp1 12392	. . . . . . . 8 |- ( x e. NN -> prod_ k e. ( 1 ... ( x + 1 ) ) k = ( prod_ k e. ( 1 ... x ) k x. ( x + 1 ) ) )
35	27, 34	eqeq12d 2253	. . . . . . 7 |- ( x e. NN -> ( ( ! ` ( x + 1 ) ) = prod_ k e. ( 1 ... ( x + 1 ) ) k <-> ( ( ! ` x ) x. ( x + 1 ) ) = ( prod_ k e. ( 1 ... x ) k x. ( x + 1 ) ) ) )
36	35	adantr 276	. . . . . 6 |- ( ( x e. NN /\ ( ! ` x ) = prod_ k e. ( 1 ... x ) k ) -> ( ( ! ` ( x + 1 ) ) = prod_ k e. ( 1 ... ( x + 1 ) ) k <-> ( ( ! ` x ) x. ( x + 1 ) ) = ( prod_ k e. ( 1 ... x ) k x. ( x + 1 ) ) ) )
37	24, 36	mpbird 167	. . . . 5 |- ( ( x e. NN /\ ( ! ` x ) = prod_ k e. ( 1 ... x ) k ) -> ( ! ` ( x + 1 ) ) = prod_ k e. ( 1 ... ( x + 1 ) ) k )
38	37	ex 115	. . . 4 |- ( x e. NN -> ( ( ! ` x ) = prod_ k e. ( 1 ... x ) k -> ( ! ` ( x + 1 ) ) = prod_ k e. ( 1 ... ( x + 1 ) ) k ) )
39		1zzd 9682	. . . . . . 7 |- ( x = 0 -> 1 e. ZZ )
40		1cnd 8348	. . . . . . 7 |- ( x = 0 -> 1 e. CC )
41		id 19	. . . . . . . 8 |- ( k = 1 -> k = 1 )
42	41	fprod1 12386	. . . . . . 7 |- ( ( 1 e. ZZ /\ 1 e. CC ) -> prod_ k e. ( 1 ... 1 ) k = 1 )
43	39, 40, 42	syl2anc 415	. . . . . 6 |- ( x = 0 -> prod_ k e. ( 1 ... 1 ) k = 1 )
44		oveq1 6095	. . . . . . . . 9 |- ( x = 0 -> ( x + 1 ) = ( 0 + 1 ) )
45		0p1e1 9427	. . . . . . . . 9 |- ( 0 + 1 ) = 1
46	44, 45	eqtrdi 2287	. . . . . . . 8 |- ( x = 0 -> ( x + 1 ) = 1 )
47	46	oveq2d 6104	. . . . . . 7 |- ( x = 0 -> ( 1 ... ( x + 1 ) ) = ( 1 ... 1 ) )
48	47	prodeq1d 12356	. . . . . 6 |- ( x = 0 -> prod_ k e. ( 1 ... ( x + 1 ) ) k = prod_ k e. ( 1 ... 1 ) k )
49		fv0p1e1 9428	. . . . . . 7 |- ( x = 0 -> ( ! ` ( x + 1 ) ) = ( ! ` 1 ) )
50		fac1 11189	. . . . . . 7 |- ( ! ` 1 ) = 1
51	49, 50	eqtrdi 2287	. . . . . 6 |- ( x = 0 -> ( ! ` ( x + 1 ) ) = 1 )
52	43, 48, 51	3eqtr4rd 2282	. . . . 5 |- ( x = 0 -> ( ! ` ( x + 1 ) ) = prod_ k e. ( 1 ... ( x + 1 ) ) k )
53	52	a1d 22	. . . 4 |- ( x = 0 -> ( ( ! ` x ) = prod_ k e. ( 1 ... x ) k -> ( ! ` ( x + 1 ) ) = prod_ k e. ( 1 ... ( x + 1 ) ) k ) )
54	38, 53	jaoi 728	. . 3 |- ( ( x e. NN \/ x = 0 ) -> ( ( ! ` x ) = prod_ k e. ( 1 ... x ) k -> ( ! ` ( x + 1 ) ) = prod_ k e. ( 1 ... ( x + 1 ) ) k ) )
55	22, 54	sylbi 121	. 2 |- ( x e. NN0 -> ( ( ! ` x ) = prod_ k e. ( 1 ... x ) k -> ( ! ` ( x + 1 ) ) = prod_ k e. ( 1 ... ( x + 1 ) ) k ) )
56	4, 8, 12, 16, 21, 55	nn0ind 9771	1 |- ( A e. NN0 -> ( ! ` A ) = prod_ k e. ( 1 ... A ) k )

This proof depends on syntax axioms:   -> wi 4   /\ wa 104   <-> wb 105   \/ wo 720   = wceq 1402   e. wcel 2209   (/)c0 3520   ` cfv 5380  (class class class)co 6088   CCcc 8183   0cc0 8185   1c1 8186   + caddc 8188   x. cmul 8190   NNcn 9313   NN0cn0 9574   ZZcz 9655   ZZ>=cuz 9937   ...cfz 10428   !cfa 11185   prod_cprod 12342

This proof depends on axioms:  ax-mp 5  ax-1 6  ax-2 7  ax-ia1 106  ax-ia2 107  ax-ia3 108  ax-in1 623  ax-in2 624  ax-io 721  ax-5 1500  ax-7 1501  ax-gen 1502  ax-ie1 1546  ax-ie2 1547  ax-8 1557  ax-10 1558  ax-11 1559  ax-i12 1560  ax-bndl 1562  ax-4 1563  ax-17 1579  ax-i9 1583  ax-ial 1587  ax-i5r 1588  ax-14 2212  ax-ext 2220  ax-coll 4248  ax-sep 4251  ax-nul 4261  ax-pow 4313  ax-pr 4348  ax-un 4580  ax-setind 4686  ax-iinf 4737  ax-cnex 8276  ax-resscn 8277  ax-1cn 8278  ax-1re 8279  ax-icn 8280  ax-addcl 8281  ax-addrcl 8282  ax-mulcl 8283  ax-mulrcl 8284  ax-addcom 8285  ax-mulcom 8286  ax-addass 8287  ax-mulass 8288  ax-distr 8289  ax-i2m1 8290  ax-0lt1 8291  ax-1rid 8292  ax-0id 8293  ax-rnegex 8294  ax-precex 8295  ax-cnre 8296  ax-pre-ltirr 8297  ax-pre-ltwlin 8298  ax-pre-lttrn 8299  ax-pre-apti 8300  ax-pre-ltadd 8301  ax-pre-mulgt0 8302  ax-pre-mulext 8303  ax-arch 8304  ax-caucvg 8305

This proof depends on definitions:  df-bi 117  df-dc 847  df-3or 1010  df-3an 1011  df-tru 1405  df-fal 1408  df-nf 1514  df-sb 1816  df-eu 2089  df-mo 2090  df-clab 2225  df-cleq 2231  df-clel 2234  df-nfc 2381  df-ne 2421  df-nel 2516  df-ral 2533  df-rex 2534  df-reu 2535  df-rmo 2536  df-rab 2537  df-v 2823  df-sbc 3052  df-csb 3148  df-dif 3222  df-un 3224  df-in 3226  df-ss 3233  df-nul 3521  df-if 3639  df-pw 3690  df-sn 3715  df-pr 3716  df-op 3718  df-uni 3936  df-int 3971  df-iun 4014  df-br 4132  df-opab 4194  df-mpt 4195  df-tr 4232  df-id 4440  df-po 4443  df-iso 4444  df-iord 4513  df-on 4515  df-ilim 4516  df-suc 4518  df-iom 4740  df-xp 4782  df-rel 4783  df-cnv 4784  df-co 4785  df-dm 4786  df-rn 4787  df-res 4788  df-ima 4789  df-iota 5340  df-fun 5382  df-fn 5383  df-f 5384  df-f1 5385  df-fo 5386  df-f1o 5387  df-fv 5388  df-isom 5389  df-riota 6041  df-ov 6091  df-oprab 6092  df-mpo 6093  df-1st 6378  df-2nd 6379  df-recs 6580  df-irdg 6645  df-frec 6666  df-1o 6691  df-oadd 6695  df-er 6811  df-en 7027  df-dom 7028  df-fin 7029  df-pnf 8368  df-mnf 8369  df-xr 8370  df-ltxr 8371  df-le 8372  df-sub 8506  df-neg 8507  df-reap 8911  df-ap 8918  df-div 9011  df-inn 9314  df-2 9372  df-3 9373  df-4 9374  df-n0 9575  df-z 9656  df-uz 9938  df-q 10036  df-rp 10072  df-fz 10429  df-fzo 10567  df-seqfrec 10906  df-exp 10997  df-fac 11186  df-ihash 11237  df-cj 11629  df-re 11630  df-im 11631  df-rsqrt 11786  df-abs 11787  df-clim 12070  df-proddc 12343

This theorem is used by:  gausslemma2dlem1  16385  gausslemma2dlem6  16391