Theorem basendx 13409

Description: Index value of the base set extractor.

Use of this theorem is discouraged since the particular value 1 for the index is an implementation detail. It is generally sufficient to work with (Base‘ndx) and use theorems such as baseid 13408 and basendxnn 13410.

The main circumstance in which it is necessary to look at indices directly is when showing that a set of indices are disjoint, in proofs such as lmodstrd 13520. Although we have a few theorems such as basendxnplusgndx 13481, we do not intend to add such theorems for every pair of indices (which would be quadradically many in the number of indices).

(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 13360	. 2 ⊢ Base = Slot 1
2		1nn 9316	. 2 ⊢ 1 ∈ ℕ
3	1, 2	ndxarg 13377	1 ⊢ (Base‘ndx) = 1

This proof depends on syntax axioms:   = wceq 1402  ‘cfv 5377  1c1 8180  ndxcnx 13351  Basecbs 13354

This proof depends on axioms:  ax-mp 5  ax-1 6  ax-2 7  ax-ia1 106  ax-ia2 107  ax-ia3 108  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-sep 4249  ax-pow 4311  ax-pr 4346  ax-un 4578  ax-cnex 8270  ax-resscn 8271  ax-1re 8273  ax-addrcl 8276

This proof depends on definitions:  df-bi 117  df-3an 1011  df-tru 1405  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-ral 2533  df-rex 2534  df-v 2823  df-sbc 3052  df-un 3224  df-in 3226  df-ss 3233  df-pw 3690  df-sn 3715  df-pr 3716  df-op 3718  df-uni 3936  df-int 3971  df-br 4131  df-opab 4193  df-mpt 4194  df-id 4438  df-xp 4780  df-rel 4781  df-cnv 4782  df-co 4783  df-dm 4784  df-rn 4785  df-res 4786  df-iota 5337  df-fun 5379  df-fv 5385  df-inn 9306  df-ndx 13357  df-slot 13358  df-base 13360

This theorem is used by:  basendxltplusgndx  13469  1strstrg  13472  2strstrg  13475  2strbasg  13476  2stropg  13477  2strstr1g  13478  rngstrg  13491  starvndxnbasendx  13498  scandxnbasendx  13510  vscandxnbasendx  13515  lmodstrd  13520  ipndxnbasendx  13528  basendxlttsetndx  13546  topgrpstrd  13552  basendxltplendx  13560  basendxnocndx  13569  basendxltdsndx  13575  basendxltunifndx  13585  setsmsbasg  15582  basendxltedgfndx  16263