11. A computer implemented method of information retrieval, comprising: parsing a corpus to identify instances of wordforms within each document of the corpus; performing a morphological tokenization on the wordforms to convert the wordforms into morphemes by separating affixes from their stems; generating a morpheme-by-document matrix based at least in part on a number of instances of the affixes and the stems within each document of the corpus, wherein the morpheme-by-document matrix accounts for information related to past tense and present tense inflections by separately enumerating the instances of the affixes from the instances of the stems; generating a term-by-term alignment matrix based at least in part on the number of instances of the affixes and the stems within each document of the corpus and the morpheme-by-document matrix; and generating at least one lower rank approximation matrix by factorizing the term-by-term alignment matrix.
11. A computer implemented method of information retrieval, comprising: parsing a corpus to identify instances of wordforms within each document of the corpus; performing a morphological tokenization on the wordforms to convert the wordforms into morphemes by separating affixes from their stems; generating a morpheme-by-document matrix based at least in part on a number of instances of the affixes and the stems within each document of the corpus, wherein the morpheme-by-document matrix accounts for information related to past tense and present tense inflections by separately enumerating the instances of the affixes from the instances of the stems; generating a term-by-term alignment matrix based at least in part on the number of instances of the affixes and the stems within each document of the corpus and the morpheme-by-document matrix; and generating at least one lower rank approximation matrix by factorizing the term-by-term alignment matrix. 15. The computer implemented method of claim 11 , wherein the term-by-term alignment matrix comprises a weighted term-by-term alignment matrix.