In the future, you can prove it. Probably best as a lemma. Let ph -> T e. CC
and ph -> T + 1 in ZZ

So, T + 1 - 1 in ZZ, and by cancellation, T in ZZ. You can see an example
at https://us.metamath.org/mpeuni/readdrcl2d.html

On Tue, Apr 29, 2025 at 1:21 PM Ender Ting <[email protected]>
wrote:

> I've managed to get unstuck, bringing one more antecedent into the
> expression! Here's the script of my current progress.
>
> $( <MM> <PROOF_ASST> THEOREM=ormkglobd  LOC_AFTER=et-sqrtnegnre
>
> h1::ormkglobd.1 |- ( ph -> R Or S )
> h2::ormkglobd.2 |- ( ph -> ran B C_ S )
> h3::ormkglobd.3 |- ( ph -> A. k e. ( 0 ..^ T ) ( B ` k ) R ( B ` ( k + 1 )
> ) )
> * bringing a hypothesis that <T e. ZZ> here looks unnecessary; theorem
> still holds
>   even if non-integer T is substituted
>
> d2:3:r19.21bi |- ( ( ph /\ k e. ( 0 ..^ T ) ) -> ( B ` k ) R ( B ` ( k + 1
> ) ) )
> !d16::     |- (  a = ( k + 1 ) -> ( ( B ` k ) R ( B ` a ) <-> ( B ` k ) R
> ( B ` ( k + 1 ) ) ) )
> !d17::     |- (  a = b -> ( ( B ` k ) R ( B ` a ) <-> ( B ` k ) R ( B ` b
> ) ) )
> !d18::     |- (  a = ( b + 1 ) -> ( ( B ` k ) R ( B ` a ) <-> ( B ` k ) R
> ( B ` ( b + 1 ) ) ) )
> !d19::     |- (  a = t -> ( ( B ` k ) R ( B ` a ) <-> ( B ` k ) R ( B ` t
> ) ) )
> !d21::     |- (  (  ( ph /\ k e. ( 0 ..^ T ) )
>                          /\ ( b e. ZZ /\ ( k + 1 ) <_ b /\ b < T )
>                          /\ ( B ` k ) R ( B ` b ) )
>                       -> ( B ` k ) R ( B ` ( b + 1 ) ) )
> d14::elfzoelz      |- ( k e. ( 0 ..^ T ) -> k e. ZZ )
> d15::elfzoel2      |- ( k e. ( 0 ..^ T ) -> T e. ZZ )
> d4::elfzop1le2     |- ( k e. ( 0 ..^ T ) -> ( k + 1 ) <_ T )
> d25:d14:adantl     |- (  ( ph /\ k e. ( 0 ..^ T ) ) -> k e. ZZ )
> d22:d25:peano2zd   |- (  ( ph /\ k e. ( 0 ..^ T ) ) -> ( k + 1 ) e. ZZ )
> d23:d15:adantl     |- (  ( ph /\ k e. ( 0 ..^ T ) ) -> T e. ZZ )
> d24:d4:adantl      |- (  ( ph /\ k e. ( 0 ..^ T ) ) -> ( k + 1 ) <_ T )
> d3:d16,d17,d18,d19,d2,d21,d22,d23,d24:fzindd
>                    |- (  (  ( ph /\ k e. ( 0 ..^ T ) )
>                          /\ ( t e. ZZ /\ ( k + 1 ) <_ t /\ t <_ T ) )
>                       -> ( B ` k ) R ( B ` t ) )
>
> d30::elfzop1le2  |- ( t e. ( 1 ..^ ( T + 1 ) ) -> ( t + 1 ) <_ ( T + 1 ) )
> d33::leadd1  |- (  ( t e. RR /\ T e. RR /\ 1 e. RR )
>                       -> ( t <_ T <-> ( t + 1 ) <_ ( T + 1 ) ) )
> d40:d33:biimprd |- (  ( t e. RR /\ T e. RR /\ 1 e. RR )
>                       -> ( ( t + 1 ) <_ ( T + 1 ) -> t <_ T ) )
> d32:d30:adantl |- ( ( k e. ( 0 ..^ T ) /\ t e. ( 1 ..^ ( T + 1 ) ) )
>                     -> ( t + 1 ) <_ ( T + 1 ) )
> * ********************************************************************
>   here, I tried to prove <T e. ZZ> from <t e. ( 1 ..^ ( T + 1 ) )>
>   ********************************************************************
> d34:d15:adantr |- ( ( k e. ( 0 ..^ T ) /\ t e. ( 1 ..^ ( T + 1 ) ) )
>                     -> T e. ZZ )
> d36::elfzoelz |- ( t e. ( 1 ..^ ( T + 1 ) ) -> t e. ZZ )
> d35:d36:adantl |- ( ( k e. ( 0 ..^ T ) /\ t e. ( 1 ..^ ( T + 1 ) ) )
>                     -> t e. ZZ )
> d38:d34:zred |- ( ( k e. ( 0 ..^ T ) /\ t e. ( 1 ..^ ( T + 1 ) ) ) -> T e.
> RR )
> d37:d35:zred |- ( ( k e. ( 0 ..^ T ) /\ t e. ( 1 ..^ ( T + 1 ) ) ) -> t e.
> RR )
> d39::1red |- ( ( k e. ( 0 ..^ T ) /\ t e. ( 1 ..^ ( T + 1 ) ) ) -> 1 e. RR
> )
> d41:d37,d38,d39:3jca |- ( ( k e. ( 0 ..^ T ) /\ t e. ( 1 ..^ ( T + 1 ) ) )
>                     ->  ( t e. RR /\ T e. RR /\ 1 e. RR ) )
> d31:d41,d32,d40:sylc |- ( ( k e. ( 0 ..^ T ) /\ t e. ( 1 ..^ ( T + 1 ) ) )
>                     -> t <_ T )
> d42:d14:adantr |- ( ( k e. ( 0 ..^ T ) /\ t e. ( 1 ..^ ( T + 1 ) ) )
>                -> k e. ZZ )
> d43::zltp1le   |- ( ( k e. ZZ /\ t e. ZZ ) -> ( k < t <-> ( k + 1 ) <_ t )
> )
> d44:d42,d35,d43:syl2anc |- ( ( k e. ( 0 ..^ T ) /\ t e. ( 1 ..^ ( T + 1 )
> ) )
>            -> ( k < t <-> ( k + 1 ) <_ t ) )
> d45:d44:biimpd |- ( ( k e. ( 0 ..^ T ) /\ t e. ( 1 ..^ ( T + 1 ) ) )
>            -> ( k < t -> ( k + 1 ) <_ t ) )
> d46:d35:a1d |- ( ( k e. ( 0 ..^ T ) /\ t e. ( 1 ..^ ( T + 1 ) ) )
>            -> ( k < t -> t e. ZZ ) )
> d47:d31:a1d |- ( ( k e. ( 0 ..^ T ) /\ t e. ( 1 ..^ ( T + 1 ) ) )
>            -> ( k < t -> t <_ T ) )
> d48:d46,d45,d47:3jcad |- ( ( k e. ( 0 ..^ T ) /\ t e. ( 1 ..^ ( T + 1 ) ) )
>            -> ( k < t -> ( t e. ZZ /\ ( k + 1 ) <_ t /\ t <_ T ) ) )
> d52::2a1 |- ( ph -> ( ( k e. ( 0 ..^ T ) /\ t e. ( 1 ..^ ( T + 1 ) ) )
>            -> ( k < t -> ph ) ) )
> d53:d48:a1i |- ( ph -> ( ( k e. ( 0 ..^ T ) /\ t e. ( 1 ..^ ( T + 1 ) ) )
>            -> ( k < t -> ( t e. ZZ /\ ( k + 1 ) <_ t /\ t <_ T ) ) ) )
> d55::2a1 |- ( k e. ( 0 ..^ T ) -> ( t e. ( 1 ..^ ( T + 1 ) )
>            -> ( k < t -> k e. ( 0 ..^ T ) ) ) )
> d54:d55:imp |- ( ( k e. ( 0 ..^ T ) /\ t e. ( 1 ..^ ( T + 1 ) ) )
>            -> ( k < t -> k e. ( 0 ..^ T ) ) )
> d51:d54:a1i |- ( ph -> ( ( k e. ( 0 ..^ T ) /\ t e. ( 1 ..^ ( T + 1 ) ) )
>            -> ( k < t -> k e. ( 0 ..^ T ) ) ) )
> !d56::jcad |- ( ph -> ( ( k e. ( 0 ..^ T ) /\ t e. ( 1 ..^ ( T + 1 ) ) )
>            -> ( k < t -> ( ph /\ k e. ( 0 ..^ T ) ) ) ) )
>
> d49::  |- ( ( ph /\ &W1 ) -> ( B ` k ) R ( B ` t ) )
> d50::         |- (  ph
>                       -> (  (  k e. ( 0 ..^ T )
>                             /\ t e. ( 1 ..^ ( T + 1 ) ) )
>                          -> ( k < t -> ( ph /\ &W1 ) ) ) )
>
> d1:d50,d49:syl8 |- (  ph
>                       -> (  (  k e. ( 0 ..^ T )
>                             /\ t e. ( 1 ..^ ( T + 1 ) ) )
>                          -> ( k < t -> ( B ` k ) R ( B ` t ) ) ) )
> qed:d1:ralrimivv |- ( ph -> A. k e. ( 0 ..^ T ) A. t e. ( 1 ..^ ( T + 1 ) )
>     ( k < t -> ( B ` k ) R ( B ` t ) ) )
>
> $)
>
> Well, I get the reason: if addition was defined to return 0 or like on
> non-integer arguments, then cancellation would not work. Thanks for the
> answer!
> вторник, 29 апреля 2025 г. в 21:05:51 UTC+3, Meta Kunt:
>
>> Yes and no.
>> Yes you can prove it, but it involves internal details of how addition is
>> defined. Reverse closure laws are explicitly not proven for addition.
>> Why do you have this assertion? If you know that ( ph -> ( T + 1 ) e. ZZ
>> ) why not just say that ( ph -> T e. ZZ ).
>>
>> Also if you could paste your proof script that would be nice so that we
>> could see where you are stuck.
>>
>> ­
>>
>> *Von:* Ender Ting <[email protected]>
>> *Datum:* 29.04.2025 19:49:26
>> *An:* Metamath <[email protected]>
>> *Betreff:* [Metamath] Utility theorems for numbers
>> Hi! I've tried to reprove my ~ natglobalincr in a more general way, and
>> managed to hit a problem.
>>
>> I have a "( ph -> ( T + 1 ) e. ZZ )" assertion. It turns out there are
>> zero theorems which allow to go from that to "( ph -> T e. ZZ )", while it
>> seems there really should be some.
>> Is there a way to prove it?
>> Thanks!
>>
>> ---
>> Ender Ting
>>
>>
>> P.S. I can work around this because the final theorem contains "A. k e. (
>> 0 ..^ T )" which would generalize over empty set if T is not integer, but
>> that makes proof very much cumbersome.
>>
>>
>>
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