<keyword>symmetry</keyword>
<keyword>simplify</keyword>
<keyword>split</keyword>
+ <keyword>subst</keyword>
<keyword>to</keyword>
<keyword>transitivity</keyword>
<keyword>unfold</keyword>
<keyword>first</keyword>
<keyword>focus</keyword>
<keyword>unfocus</keyword>
+ <keyword>progress</keyword>
</keyword-list>