I was trying to install Skype on Ubuntu 13.04, from the Canonical repositories. With apt-get it worked easily, while aptitude had a huge problem with dependencies and proposed a complicated solution. Why is this so? Why doesn't aptitude offer whatever apt-get does as a potential solution? Here is the output of both:

apt-get install skype:

Reading package lists...
Building dependency tree...
Reading state information...
The following extra packages will be installed:
  gcc-4.7-base:i386 libasound2 libasound2:i386 libasound2-plugins:i386
  libasyncns0:i386 libaudio2:i386 libavahi-client3:i386
  libavahi-common-data:i386 libavahi-common3:i386 libc6:i386 libcomerr2:i386
  libcups2:i386 libdbus-1-3 libdbus-1-3:i386 libdbusmenu-qt2:i386
  libdrm-intel1 libdrm-intel1:i386 libdrm-nouveau2 libdrm-nouveau2:i386
  libdrm-radeon1 libdrm-radeon1:i386 libdrm2 libdrm2:i386 libexpat1:i386
  libffi6:i386 libflac8:i386 libfontconfig1:i386 libfreetype6:i386
  libgcc1:i386 libgcrypt11 libgcrypt11:i386 libgl1-mesa-dri
  libgl1-mesa-dri:i386 libgl1-mesa-glx:i386 libglapi-mesa:i386
  libglib2.0-0:i386 libgnutls26 libgnutls26:i386 libgpg-error0:i386
  libgssapi-krb5-2:i386 libgstreamer-plugins-base0.10-0:i386
  libgstreamer0.10-0:i386 libice6:i386 libjack-jackd2-0:i386 libjbig0:i386
  libjpeg-turbo8:i386 libjpeg8:i386 libjson0:i386 libk5crypto3:i386
  libkeyutils1:i386 libkrb5-3:i386 libkrb5support0:i386 liblcms1:i386
  libllvm3.2:i386 liblzma5:i386 libmng1:i386 libmysqlclient18:i386
  libogg0:i386 liborc-0.4-0:i386 libp11-kit0:i386 libpciaccess0:i386
  libpcre3:i386 libpng12-0:i386 libpulse0:i386 libqt4-dbus libqt4-dbus:i386
  libqt4-declarative libqt4-declarative:i386 libqt4-designer libqt4-help
  libqt4-network libqt4-network:i386 libqt4-opengl libqt4-opengl:i386
  libqt4-script libqt4-script:i386 libqt4-scripttools libqt4-sql
  libqt4-sql:i386 libqt4-sql-mysql:i386 libqt4-sql-sqlite libqt4-svg
  libqt4-test libqt4-xml libqt4-xml:i386 libqt4-xmlpatterns
  libqt4-xmlpatterns:i386 libqtcore4 libqtcore4:i386 libqtgui4 libqtgui4:i386
  libqtwebkit4:i386 libsamplerate0:i386 libselinux1:i386 libsm6:i386
  libsndfile1:i386 libspeexdsp1:i386 libsqlite3-0:i386 libssl1.0.0
  libssl1.0.0:i386 libstdc++6:i386 libtasn1-3:i386 libtiff5 libtiff5:i386
  libtxc-dxtn-s2tc0:i386 libuuid1:i386 libvorbis0a:i386 libvorbisenc2:i386
  libwrap0:i386 libx11-6 libx11-6:i386 libx11-xcb1 libx11-xcb1:i386
  libxau6:i386 libxcb-dri2-0 libxcb-dri2-0:i386 libxcb-glx0 libxcb-glx0:i386
  libxcb1 libxcb1:i386 libxdamage1:i386 libxdmcp6:i386 libxext6 libxext6:i386
  libxfixes3 libxfixes3:i386 libxi6 libxi6:i386 libxml2 libxml2:i386
  libxrender1 libxrender1:i386 libxslt1.1:i386 libxss1:i386 libxt6 libxt6:i386
  libxv1 libxv1:i386 libxxf86vm1 libxxf86vm1:i386 mysql-common qdbus
  skype-bin:i386 sni-qt:i386 zlib1g:i386
Suggested packages:
  nas:i386 glibc-doc:i386 locales:i386 rng-tools rng-tools:i386 libglide3
  libglide3:i386 gnutls-bin gnutls-bin:i386 krb5-doc:i386 krb5-user:i386
  libvisual-0.4-plugins:i386 gstreamer-codec-install:i386
  gnome-codec-install:i386 gstreamer0.10-tools:i386
  gstreamer0.10-plugins-base:i386 jackd2:i386 liblcms-utils:i386
  pulseaudio:i386 libqt4-declarative-folderlistmodel
  libqt4-declarative-gestures libqt4-declarative-particles
  libqt4-declarative-shaders qt4-qmlviewer
  libqt4-declarative-folderlistmodel:i386 libqt4-declarative-gestures:i386
  libqt4-declarative-particles:i386 libqt4-declarative-shaders:i386
  qt4-qmlviewer:i386 libqt4-dev libqt4-dev:i386 libthai0:i386 libicu48:i386
  qt4-qtconfig qt4-qtconfig:i386
Recommended packages:
  libtxc-dxtn0:i386 xml-core:i386
The following NEW packages will be installed
  gcc-4.7-base:i386 libasound2:i386 libasound2-plugins:i386 libasyncns0:i386
  libaudio2:i386 libavahi-client3:i386 libavahi-common-data:i386
  libavahi-common3:i386 libc6:i386 libcomerr2:i386 libcups2:i386
  libdbus-1-3:i386 libdbusmenu-qt2:i386 libdrm-intel1:i386
  libdrm-nouveau2:i386 libdrm-radeon1:i386 libdrm2:i386 libexpat1:i386
  libffi6:i386 libflac8:i386 libfontconfig1:i386 libfreetype6:i386
  libgcc1:i386 libgcrypt11:i386 libgl1-mesa-dri:i386 libgl1-mesa-glx:i386
  libglapi-mesa:i386 libglib2.0-0:i386 libgnutls26:i386 libgpg-error0:i386
  libgssapi-krb5-2:i386 libgstreamer-plugins-base0.10-0:i386
  libgstreamer0.10-0:i386 libice6:i386 libjack-jackd2-0:i386 libjbig0:i386
  libjpeg-turbo8:i386 libjpeg8:i386 libjson0:i386 libk5crypto3:i386
  libkeyutils1:i386 libkrb5-3:i386 libkrb5support0:i386 liblcms1:i386
  libllvm3.2:i386 liblzma5:i386 libmng1:i386 libmysqlclient18:i386
  libogg0:i386 liborc-0.4-0:i386 libp11-kit0:i386 libpciaccess0:i386
  libpcre3:i386 libpng12-0:i386 libpulse0:i386 libqt4-dbus:i386
  libqt4-declarative:i386 libqt4-network:i386 libqt4-opengl:i386
  libqt4-script:i386 libqt4-sql:i386 libqt4-sql-mysql:i386 libqt4-xml:i386
  libqt4-xmlpatterns:i386 libqtcore4:i386 libqtgui4:i386 libqtwebkit4:i386
  libsamplerate0:i386 libselinux1:i386 libsm6:i386 libsndfile1:i386
  libspeexdsp1:i386 libsqlite3-0:i386 libssl1.0.0:i386 libstdc++6:i386
  libtasn1-3:i386 libtiff5:i386 libtxc-dxtn-s2tc0:i386 libuuid1:i386
  libvorbis0a:i386 libvorbisenc2:i386 libwrap0:i386 libx11-6:i386
  libx11-xcb1:i386 libxau6:i386 libxcb-dri2-0:i386 libxcb-glx0:i386
  libxcb1:i386 libxdamage1:i386 libxdmcp6:i386 libxext6:i386 libxfixes3:i386
  libxi6:i386 libxml2:i386 libxrender1:i386 libxslt1.1:i386 libxss1:i386
  libxt6:i386 libxv1:i386 libxxf86vm1:i386 mysql-common skype skype-bin:i386
  sni-qt:i386 zlib1g:i386
The following packages will be upgraded:
  libasound2 libdbus-1-3 libdrm-intel1 libdrm-nouveau2 libdrm-radeon1 libdrm2
  libgcrypt11 libgl1-mesa-dri libgnutls26 libqt4-dbus libqt4-declarative
  libqt4-designer libqt4-help libqt4-network libqt4-opengl libqt4-script
  libqt4-scripttools libqt4-sql libqt4-sql-sqlite libqt4-svg libqt4-test
  libqt4-xml libqt4-xmlpatterns libqtcore4 libqtgui4 libssl1.0.0 libtiff5
  libx11-6 libx11-xcb1 libxcb-dri2-0 libxcb-glx0 libxcb1 libxext6 libxfixes3
  libxi6 libxml2 libxrender1 libxt6 libxv1 libxxf86vm1 qdbus
41 upgraded, 105 newly installed, 0 to remove and 138 not upgraded.
Need to get 85.9 MB/89.2 MB of archives.
After this operation, 204 MB of additional disk space will be used.
Do you want to continue [Y/n]?

aptitude install skype:

Reading package lists...
Building dependency tree...
Reading state information...
Reading extended state information...
Initialising package states...
The following NEW packages will be installed:
  gcc-4.7-base:i386{a} libasound2:i386{a} libasound2-plugins:i386{a} 
  libasyncns0:i386{a} libaudio2:i386{a} libavahi-client3:i386{a} 
  libavahi-common-data:i386{a} libavahi-common3:i386{a} libc6:i386{a} 
  libcomerr2:i386{a} libcups2:i386{a} libdbus-1-3:i386{a} 
  libdbusmenu-qt2:i386{a} libdrm-intel1:i386{a} libdrm-nouveau2:i386{a} 
  libdrm-radeon1:i386{a} libdrm2:i386{a} libexpat1:i386{a} libffi6:i386{a} 
  libflac8:i386{a} libfontconfig1:i386{a} libfreetype6:i386{a} 
  libgcc1:i386{a} libgcrypt11:i386{a} libgl1-mesa-dri:i386{a} 
  libgl1-mesa-glx:i386{a} libglapi-mesa:i386{a} libglib2.0-0:i386{a} 
  libgnutls26:i386{a} libgpg-error0:i386{a} libgssapi-krb5-2:i386{a} 
  libgstreamer-plugins-base0.10-0:i386{a} libgstreamer0.10-0:i386{a} 
  libice6:i386{a} libjack-jackd2-0:i386{a} libjbig0:i386{a} 
  libjpeg-turbo8:i386{a} libjpeg8:i386{a} libjson0:i386{a} 
  libk5crypto3:i386{a} libkeyutils1:i386{a} libkrb5-3:i386{a} 
  libkrb5support0:i386{a} liblcms1:i386{a} libllvm3.2:i386{a} 
  liblzma5:i386{a} libmng1:i386{a} libmysqlclient18:i386{a} libogg0:i386{a} 
  liborc-0.4-0:i386{a} libp11-kit0:i386{a} libpciaccess0:i386{a} 
  libpcre3:i386{a} libpng12-0:i386{a} libpulse0:i386{a} libqt4-dbus:i386{a} 
  libqt4-declarative:i386{a} libqt4-network:i386{a} libqt4-opengl:i386{a} 
  libqt4-script:i386{a} libqt4-sql:i386{a} libqt4-sql-mysql:i386{a} 
  libqt4-xml:i386{a} libqt4-xmlpatterns:i386{a} libqtcore4:i386{a} 
  libqtgui4:i386{a} libqtwebkit4:i386{a} libsamplerate0:i386{a} 
  libselinux1:i386{a} libsm6:i386{a} libsndfile1:i386{a} 
  libspeexdsp1:i386{a} libsqlite3-0:i386{a} libssl1.0.0:i386{a} 
  libstdc++6:i386{a} libtasn1-3:i386{a} libtiff5:i386{a} 
  libtxc-dxtn-s2tc0:i386{a} libuuid1:i386{a} libvorbis0a:i386{a} 
  libvorbisenc2:i386{a} libwrap0:i386{a} libx11-6:i386{a} 
  libx11-xcb1:i386{a} libxau6:i386{a} libxcb-dri2-0:i386{a} 
  libxcb-glx0:i386{a} libxcb1:i386{a} libxdamage1:i386{a} libxdmcp6:i386{a} 
  libxext6:i386{a} libxfixes3:i386{a} libxi6:i386{a} libxml2:i386{a} 
  libxrender1:i386{a} libxslt1.1:i386{a} libxss1:i386{a} libxt6:i386{a} 
  libxv1:i386{a} libxxf86vm1:i386{a} mysql-common{a} skype 
  skype-bin:i386{a} sni-qt:i386{a} zlib1g:i386{a} 
The following packages will be upgraded:
  libasound2 libdbus-1-3 libdrm-intel1 libdrm-nouveau2 libdrm-radeon1 
  libdrm2 libgcrypt11 libgl1-mesa-dri libgnutls26 libqt4-dbus 
  libqt4-declarative libqt4-network libqt4-opengl libqt4-script libqt4-sql 
  libqt4-xml libqt4-xmlpatterns libqtcore4 libqtgui4 libssl1.0.0 libtiff5 
  libx11-6 libx11-xcb1 libxcb-dri2-0 libxcb-glx0 libxcb1 libxext6 
  libxfixes3 libxi6 libxml2 libxrender1 libxt6 libxv1 libxxf86vm1 qdbus 
35 packages upgraded, 105 newly installed, 0 to remove and 144 not upgraded.
Need to get 81.7 MB/85.0 MB of archives. After unpacking 204 MB will be used.
The following packages have unmet dependencies:
 libqt4-test : Depends: libqtcore4 (= 4:4.8.4+dfsg-0ubuntu9) but 4:4.8.4+dfsg-0ubuntu9.2 is to be installed.
 libqt4-designer : Depends: libqt4-script (= 4:4.8.4+dfsg-0ubuntu9) but 4:4.8.4+dfsg-0ubuntu9.2 is to be installed.
                   Depends: libqt4-xml (= 4:4.8.4+dfsg-0ubuntu9) but 4:4.8.4+dfsg-0ubuntu9.2 is to be installed.
                   Depends: libqtcore4 (= 4:4.8.4+dfsg-0ubuntu9) but 4:4.8.4+dfsg-0ubuntu9.2 is to be installed.
                   Depends: libqtgui4 (= 4:4.8.4+dfsg-0ubuntu9) but 4:4.8.4+dfsg-0ubuntu9.2 is to be installed.
 libqt4-sql-sqlite : Depends: libqt4-sql (= 4:4.8.4+dfsg-0ubuntu9) but 4:4.8.4+dfsg-0ubuntu9.2 is to be installed.
                     Depends: libqtcore4 (= 4:4.8.4+dfsg-0ubuntu9) but 4:4.8.4+dfsg-0ubuntu9.2 is to be installed.
 libqt4-help : Depends: libqt4-network (= 4:4.8.4+dfsg-0ubuntu9) but 4:4.8.4+dfsg-0ubuntu9.2 is to be installed.
               Depends: libqt4-sql (= 4:4.8.4+dfsg-0ubuntu9) but 4:4.8.4+dfsg-0ubuntu9.2 is to be installed.
               Depends: libqtcore4 (= 4:4.8.4+dfsg-0ubuntu9) but 4:4.8.4+dfsg-0ubuntu9.2 is to be installed.
               Depends: libqtgui4 (= 4:4.8.4+dfsg-0ubuntu9) but 4:4.8.4+dfsg-0ubuntu9.2 is to be installed.
 libqt4-svg : Depends: libqtcore4 (= 4:4.8.4+dfsg-0ubuntu9) but 4:4.8.4+dfsg-0ubuntu9.2 is to be installed.
              Depends: libqtgui4 (= 4:4.8.4+dfsg-0ubuntu9) but 4:4.8.4+dfsg-0ubuntu9.2 is to be installed.
 libqt4-scripttools : Depends: libqt4-script (= 4:4.8.4+dfsg-0ubuntu9) but 4:4.8.4+dfsg-0ubuntu9.2 is to be installed.
                      Depends: libqtcore4 (= 4:4.8.4+dfsg-0ubuntu9) but 4:4.8.4+dfsg-0ubuntu9.2 is to be installed.
                      Depends: libqtgui4 (= 4:4.8.4+dfsg-0ubuntu9) but 4:4.8.4+dfsg-0ubuntu9.2 is to be installed.
The following actions will resolve these dependencies:

      Remove the following packages:                                            
1)      account-plugin-aim                                                      
2)      account-plugin-facebook                                                 
3)      account-plugin-flickr                                                   
4)      account-plugin-generic-oauth                                            
5)      account-plugin-google                                                   
6)      account-plugin-jabber                                                   
7)      account-plugin-salut                                                    
8)      account-plugin-twitter                                                  
9)      account-plugin-windows-live                                             
10)     account-plugin-yahoo                                                    
11)     empathy                                                                 
12)     friends                                                                 
13)     friends-dispatcher                                                      
14)     friends-facebook                                                        
15)     friends-twitter                                                         
16)     gir1.2-signon-1.0                                                       
17)     gnome-control-center-signon                                             
18)     libaccount-plugin-1.0-0                                                 
19)     libfriends0                                                             
20)     libqt4-designer                                                         
21)     libqt4-help                                                             
22)     libqt4-scripttools                                                      
23)     libqt4-sql-sqlite                                                       
24)     libqt4-svg                                                              
25)     libqt4-test                                                             
26)     libsignon-glib1                                                         
27)     mcp-account-manager-uoa                                                 
28)     nautilus-sendto-empathy                                                 
29)     python-qt4                                                              
30)     shotwell                                                                
31)     signon-plugin-oauth2                                                    
32)     signon-plugin-password                                                  
33)     signon-ui                                                               
34)     signond                                                                 
35)     ubuntu-sso-client-qt                                                    
36)     ubuntuone-control-panel-qt                                              
37)     unity-lens-friends                                                      
38)     unity-lens-photos                                                       
39)     unity-scope-gdrive                                                      
40)     webaccounts-extension-common                                            
41)     xul-ext-webaccounts                                                     

      Leave the following dependencies unresolved:                              
42)     mcp-account-manager-uoa recommends gnome-control-center-signon          
43)     mcp-account-manager-uoa recommends account-plugin-aim                   
44)     mcp-account-manager-uoa recommends account-plugin-jabber                
45)     mcp-account-manager-uoa recommends account-plugin-google                
46)     mcp-account-manager-uoa recommends account-plugin-facebook              
47)     mcp-account-manager-uoa recommends account-plugin-windows-live          
48)     mcp-account-manager-uoa recommends account-plugin-yahoo                 
49)     mcp-account-manager-uoa recommends account-plugin-salut                 
50)     ubuntu-desktop recommends empathy                                       
51)     ubuntu-desktop recommends libqt4-sql-sqlite                             
52)     ubuntu-desktop recommends shotwell                                      
53)     ubuntu-desktop recommends ubuntuone-control-panel-qt                    
54)     ubuntu-desktop recommends xul-ext-webaccounts                           
55)     unity recommends unity-lens-photos                                      
56)     unity recommends unity-lens-friends                                     
57)     unity-lens-files recommends unity-scope-gdrive                          
58)     libqt4-sql recommends libqt4-sql-mysql | libqt4-sql-odbc | libqt4-sql-ps


Accept this solution? [Y/n/q/?] 

And in case this helps, aptitude show skype:

Package: skype
State: not installed
Version: 4.2.0.11-0ubuntu0.12.04.2
Priority: extra
Section: net
Maintainer: Steve Langasek <[email protected]>
Architecture: amd64
Uncompressed Size: 62.5 k
Depends: skype-bin
Conflicts: skype
Description: client for Skype VOIP and instant messaging service
 Skype is software that enables the world's conversations.  Millions of
 individuals and businesses use Skype to make free video and voice calls, send
 instant messages and share files with other Skype users.  Every day, people
 also use Skype to make low-cost calls to landlines and mobiles. 

 * Make free Skype-to-Skype calls to anyone else, anywhere in the world. * Call
 to landlines and mobiles at great rates. * Group chat with up to 200 people or
 conference call with up to 25 others. * Free to download.