Theorem basendx 11850

Description: Index value of the base set extractor. (Normally it is preferred to work with (Base‘ndx) rather than the hard-coded 1 in order to make structure theorems portable. This is an example of how to obtain it when needed.) (New usage is discouraged.) (Contributed by Mario Carneiro, 2-Aug-2013.)

Assertion

Ref	Expression
basendx	⊢ (Base‘ndx) = 1

Proof of Theorem basendx

Step	Hyp	Ref	Expression
1		df-base 11802	. 2 ⊢ Base = Slot 1
2		1nn 8635	. 2 ⊢ 1 ∈ ℕ
3	1, 2	ndxarg 11819	1 ⊢ (Base‘ndx) = 1

Syntax hints:   = wceq 1312  ‘cfv 5079  1c1 7542  ndxcnx 11793  Basecbs 11796

This theorem was proved from axioms:  ax-1 5  ax-2 6  ax-mp 7  ax-ia1 105  ax-ia2 106  ax-ia3 107  ax-io 681  ax-5 1404  ax-7 1405  ax-gen 1406  ax-ie1 1450  ax-ie2 1451  ax-8 1463  ax-10 1464  ax-11 1465  ax-i12 1466  ax-bndl 1467  ax-4 1468  ax-13 1472  ax-14 1473  ax-17 1487  ax-i9 1491  ax-ial 1495  ax-i5r 1496  ax-ext 2095  ax-sep 4004  ax-pow 4056  ax-pr 4089  ax-un 4313  ax-cnex 7630  ax-resscn 7631  ax-1re 7633  ax-addrcl 7636

This theorem depends on definitions:  df-bi 116  df-3an 945  df-tru 1315  df-nf 1418  df-sb 1717  df-eu 1976  df-mo 1977  df-clab 2100  df-cleq 2106  df-clel 2109  df-nfc 2242  df-ral 2393  df-rex 2394  df-v 2657  df-sbc 2877  df-un 3039  df-in 3041  df-ss 3048  df-pw 3476  df-sn 3497  df-pr 3498  df-op 3500  df-uni 3701  df-int 3736  df-br 3894  df-opab 3948  df-mpt 3949  df-id 4173  df-xp 4503  df-rel 4504  df-cnv 4505  df-co 4506  df-dm 4507  df-rn 4508  df-res 4509  df-iota 5044  df-fun 5081  df-fv 5087  df-inn 8625  df-ndx 11799  df-slot 11800  df-base 11802

This theorem is referenced by:  1strstrg  11894  2strstrg  11896  2strbasg  11897  2stropg  11898  2strstr1g  11899  rngstrg  11911  lmodstrd  11929  topgrpstrd  11947  setsmsbasg  12462