Möbius inversion for the Bruhat ordering on a Weyl group
Annales scientifiques de l'École Normale Supérieure, Serie 4, Volume 4 (1971) no. 3, p. 393-398 
@article{ASENS_1971_4_4_3_393_0,
     author = {Verma, Daya-Nand},
     title = {M\"obius inversion for the Bruhat ordering on a Weyl group},
     journal = {Annales scientifiques de l'\'Ecole Normale Sup\'erieure},
     publisher = {Elsevier},
     volume = {Ser. 4, 4},
     number = {3},
     year = {1971},
     pages = {393-398},
     doi = {10.24033/asens.1215},
     zbl = {0236.20035},
     mrnumber = {45 \#139},
     language = {en},
     url = {http://www.numdam.org/item/ASENS_1971_4_4_3_393_0}
}

Verma, Daya-Nand. Möbius inversion for the Bruhat ordering on a Weyl group. Annales scientifiques de l'École Normale Supérieure, Serie 4, Volume 4 (1971) no. 3, pp. 393-398. doi : 10.24033/asens.1215. http://www.numdam.org/item/ASENS_1971_4_4_3_393_0/

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