lexa user # emerge -DNua world

These are the packages that would be merged, in order:

Calculating dependencies... done!

emerge: there are no ebuilds built with USE flags to satisfy ">=kde-base/kdelibs-4.6.2[aqua=,-kdeprefix,semantic-desktop=]".
!!! One of the following packages is required to complete your request:
- kde-base/kdelibs-4.6.2-r2 (Change USE: +semantic-desktop)
- kde-base/plasma-workspace-4.6.2-r1 (Change USE: -semantic-desktop)
(dependency required by "kde-base/plasma-workspace-4.6.2-r1" [ebuild])
(dependency required by "kde-base/kdeplasma-addons-4.6.2" [installed])
(dependency required by "@selected" [set])
(dependency required by "@world" [argument])
lexa user # vim /etc/portage/package.use 
lexa user # emerge -DNua world

These are the packages that would be merged, in order:

Calculating dependencies... done!

emerge: there are no ebuilds built with USE flags to satisfy ">=kde-base/kdelibs-4.6.2[aqua=,-kdeprefix,semantic-desktop=]".
!!! One of the following packages is required to complete your request:
- kde-base/kdelibs-4.6.2-r2 (Change USE: -semantic-desktop)
- kde-base/plasma-workspace-4.6.2-r1 (Change USE: +semantic-desktop)
(dependency required by "kde-base/plasma-workspace-4.6.2-r1" [installed])
(dependency required by "kde-base/kdeplasma-addons-4.6.2" [installed])
(dependency required by "@selected" [set])
(dependency required by "@world" [argument])
lexa user #