Otdfbt

I have a text with lots of sums where the sub/superscripts are pretty long, as in

$displaystylesum_ k=1+mina-1,b-1^ maxa-1,b-1 i_k$

and when I compile the text gets very ugly, since the size of the superscripts drag the $i_k$ part far to the right, not counting the whole empty space it creates between the sum itself...

I am trying to find a way to countour the situation, but writing
$displaystyle sum_tiny k=1+mina-1,b-1^tiny maxa-1,b-1i_k$ doesn't seem to be doing anything... Is there a way to reduce the font size so that it fits exactly in the length of the sum symbol?

Edit: minimal working example with normal and tiny (the $i_k$ is tossed all the way to the right due to the length of the sub/superscripts)

documentclass[12pt,a4paper]report

usepackageamsmath

begindocument

$displaystyle sum_k=1+mina-1,b-1^maxa-1,b-1i_k$ \
$displaystyle sum_tiny k=1+mina-1,b-1^tiny maxa-1,b-1i_k$ \ 

enddocument 

You can use the smashoperator command from mathtools , and also insist for using scriptscriptstyle instead of scriptstyle, but there might be a legibility problem:

documentclassarticle
usepackagemathtools 

begindocument

$displaystylesmashoperatorsum_k=1+min(a-1,b-1)^max(a-1,b-1)i_k$ bigskip

$displaystylesmashoperatorsum_scriptscriptstyle k=1+min(a-1,b-1)^scriptscriptstylemax(a-1,b-1)i_k$

enddocument 

To reduce the amount of visual overload inflicted on your readers, I would proceed along the following lines:

documentclassarticle
usepackageamsmath
begindocument
Put $mu(a,b)=1+mina-1,b-1$ and $nu(a,b)=maxa-1,b-1$. Then
[
sum_ k=mu(a,b)^ nu(a,b) i_k
]
is defined as dots
enddocument

You could simplify this a lot like this:

documentclass[12pt,a4paper]report
usepackageamsmath
begindocument

[
 sum_k i_k
]
with $1+min(a-1,b-1)le kle max(a-1,b-1)$

enddocument