# Extension and contraction of I to D^-1R

#### Peter

##### Well-known member
MHB Site Helper
At the bottom of page 708 in Dummit and Foote (Chapter 15, Section 15.4 Localization) we find the definition of the extension and contraction of ideals.

The notation is similar to $$\displaystyle I^e$$ and $$\displaystyle I^c$$ except that the superscripts e and c occur before the I.

Can someone please help me with the latex for these symbols?

Peter

#### MarkFL

Staff member
Use the codes:

^eI to get: $$\displaystyle ^eI$$

^cI to get: $$\displaystyle ^cI$$

#### Peter

##### Well-known member
MHB Site Helper
Use the codes:

^eI to get: $$\displaystyle ^eI$$

^cI to get: $$\displaystyle ^cI$$

Thanks Mark

Appreciate the help.

Peter

#### Evgeny.Makarov

##### Well-known member
MHB Math Scholar
See also StackExchange for some options that fine-tune the spacing.

#### Deveno

##### Well-known member
MHB Math Scholar
One thing I've noticed in latex is that if you put an "empty character" (using {}) before a preceding superscript/subscript, it seems to give better alignment with other similarly tagged symbols.