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Theorem max1ALT 12230
 Description: A number is less than or equal to the maximum of it and another. This version of max1 12229 omits the 𝐵 ∈ ℝ antecedent. Although it doesn't exploit undefined behavior, it is still considered poor style, and the use of max1 12229 is preferred. (Proof modification is discouraged.) (New usage is discouraged.) (Contributed by NM, 3-Apr-2005.)
Assertion
Ref Expression
max1ALT (𝐴 ∈ ℝ → 𝐴 ≤ if(𝐴𝐵, 𝐵, 𝐴))

Proof of Theorem max1ALT
StepHypRef Expression
1 leid 10345 . . 3 (𝐴 ∈ ℝ → 𝐴𝐴)
2 iffalse 4239 . . . 4 𝐴𝐵 → if(𝐴𝐵, 𝐵, 𝐴) = 𝐴)
32breq2d 4816 . . 3 𝐴𝐵 → (𝐴 ≤ if(𝐴𝐵, 𝐵, 𝐴) ↔ 𝐴𝐴))
41, 3syl5ibrcom 237 . 2 (𝐴 ∈ ℝ → (¬ 𝐴𝐵𝐴 ≤ if(𝐴𝐵, 𝐵, 𝐴)))
5 id 22 . . 3 (𝐴𝐵𝐴𝐵)
6 iftrue 4236 . . 3 (𝐴𝐵 → if(𝐴𝐵, 𝐵, 𝐴) = 𝐵)
75, 6breqtrrd 4832 . 2 (𝐴𝐵𝐴 ≤ if(𝐴𝐵, 𝐵, 𝐴))
84, 7pm2.61d2 172 1 (𝐴 ∈ ℝ → 𝐴 ≤ if(𝐴𝐵, 𝐵, 𝐴))
 Colors of variables: wff setvar class Syntax hints:  ¬ wn 3   → wi 4   ∈ wcel 2139  ifcif 4230   class class class wbr 4804  ℝcr 10147   ≤ cle 10287 This theorem was proved from axioms:  ax-mp 5  ax-1 6  ax-2 7  ax-3 8  ax-gen 1871  ax-4 1886  ax-5 1988  ax-6 2054  ax-7 2090  ax-8 2141  ax-9 2148  ax-10 2168  ax-11 2183  ax-12 2196  ax-13 2391  ax-ext 2740  ax-sep 4933  ax-nul 4941  ax-pow 4992  ax-pr 5055  ax-un 7115  ax-resscn 10205  ax-pre-lttri 10222 This theorem depends on definitions:  df-bi 197  df-or 384  df-an 385  df-3an 1074  df-tru 1635  df-ex 1854  df-nf 1859  df-sb 2047  df-eu 2611  df-mo 2612  df-clab 2747  df-cleq 2753  df-clel 2756  df-nfc 2891  df-ne 2933  df-nel 3036  df-ral 3055  df-rex 3056  df-rab 3059  df-v 3342  df-sbc 3577  df-csb 3675  df-dif 3718  df-un 3720  df-in 3722  df-ss 3729  df-nul 4059  df-if 4231  df-pw 4304  df-sn 4322  df-pr 4324  df-op 4328  df-uni 4589  df-br 4805  df-opab 4865  df-mpt 4882  df-id 5174  df-xp 5272  df-rel 5273  df-cnv 5274  df-co 5275  df-dm 5276  df-rn 5277  df-res 5278  df-ima 5279  df-iota 6012  df-fun 6051  df-fn 6052  df-f 6053  df-f1 6054  df-fo 6055  df-f1o 6056  df-fv 6057  df-er 7913  df-en 8124  df-dom 8125  df-sdom 8126  df-pnf 10288  df-mnf 10289  df-xr 10290  df-ltxr 10291  df-le 10292 This theorem is referenced by: (None)
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