[lemma=such] [tag=NN] [word=as] [lemma=a] [lemma=□]
[lemma=such] [tag=NN] [word=as] [lemma=a] [lemma=valid]
[lemma=such] [tag=NN] [word=as] [lemma=a] [lemma=such]
It therefore follows that there is no such thing as a valid patent on a software algorithm , including one for which no evidence of previous practice can be found to exist .