If you install a package with yum install, say pdftk, it will pull in a lot of dependencies:

pdftk.x86_64 0:1.44-10.fc18

Dependency Installed:
bouncycastle.noarch 0:1.46-6.fc18
itext-core.noarch 0:2.1.7-14.fc18
libgcj.x86_64 0:4.7.2-8.fc18
bouncycastle-mail.noarch 0:1.46-6.fc18
java-1.5.0-gcj.x86_64 0:
sinjdoc.x86_64 0:0.5-13.fc18
bouncycastle-tsp.noarch 0:1.46-5.fc18
java_cup.noarch 1:0.11a-10.fc18
itext.x86_64 0:2.1.7-14.fc18
javamail.noarch 0:1.4.3-12.fc18

yum remove pdftk will remove only that package and not all the dependencies.

But you can look at all the ‘transactions’ (install, remove etc.):

$ sudo yum history list pdftk
ID | Command line | Date and time | Action(s) | Altered
88 | install pdftk | 2012-12-14 13:35 | Install | 11
And then you can undo that transaction:

$ sudo yum history undo 88
Undoing transaction 88, from Fri Dec 14 13:35:34 2012
Dep-Install bouncycastle-1.46-6.fc18.noarch @fedora
Dep-Install bouncycastle-mail-1.46-6.fc18.noarch @fedora
Dep-Install bouncycastle-tsp-1.46-5.fc18.noarch @fedora
Dep-Install itext-2.1.7-14.fc18.x86_64 @fedora
Dep-Install itext-core-2.1.7-14.fc18.noarch @fedora
Dep-Install java-1.5.0-gcj- @fedora
Dep-Install java_cup-1:0.11a-10.fc18.noarch @fedora
Dep-Install javamail-1.4.3-12.fc18.noarch @fedora
Dep-Install libgcj-4.7.2-8.fc18.x86_64 @fedora
Install pdftk-1.44-10.fc18.x86_64 @fedora
Dep-Install sinjdoc-0.5-13.fc18.x86_64 @fedora