# Re: Re: My own sum

```Allan,

does'nt it jump out that a "pure function" approach to dummy variables
in integration and summation would solve such problems? The syntactic
level is in fact a "humanoid" version of:
Sum[F[#],{#,-a,a}]& @ dummy
Sum[F[#],{#,-a,a}]&
as it "should" be.
Thomas Lemm has a point : a set of de-dummy-fying rules could in
principle be added to Mathematica. Or not?

At 20:31 18.02.98 -0500, you wrote:
>Thomas Lemm wrote:
>>
>> I want to implement another type of Sum to treat expressions in a
>> "physical" manner. But I need to know how Mathematica tackles the
>> Problem:
>>
>> Sum[F[x],{x,-a,a}]==Sum[F[y],{y,-a,a}]
>>
>Thomas,
>In[1]:=
>Sum[F[x],{x,-a,a}]==Sum[F[y],{y,-a,a}]
>
>Out[1]=
>Sum[F[x], {x, -a, a}] == Sum[F[y], {y, -a, a}]
>
>Mathematica stops at the syntactical level.
>
>We need to buid in some way of making the syntactical forms to sam
>
>In[15]:=
>%/.x|y->xy
>
>Out[15]=
>True
>
>But we need to avoid variabel clashes and deal with depndencies amongst
>the summation variables.
>--
>Allan Hayes
>Mathematica Training and Consulting
>Leicester, UK
>hay@haystack.demon.co.uk
>http://www.haystack.demon.co.uk
>voice: +44 (0)116 271 4198
>fax: +44 (0)116 271 8642
>
>

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```

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