# Sh:677

- Shelah, S., & Spinas, O. (2000).
*On incomparability and related cardinal functions on ultraproducts of Boolean algebras*. Math. Japon.,**52**(3), 345–358. arXiv: math/9903116 MR: 1796651 -
Abstract:

Let C denote any of the following cardinal characteristics of Boolean algebras: incomparability, spread, character, \pi-character, hereditary Lindelöf number, hereditary density. It is shown to be consistent that there exists a sequence \langle B_i:i<\kappa\rangle of Boolean algebras and an ultrafilter D on \kappa such that C(\prod_{i<\kappa}B_i/D)<|\prod_{i<\kappa}C(B_i)/D|. This answers a number of problems posed by Monk. - No downloadable versions available.

Bib entry

@article{Sh:677, author = {Shelah, Saharon and Spinas, Otmar}, title = {{On incomparability and related cardinal functions on ultraproducts of Boolean algebras}}, journal = {Math. Japon.}, fjournal = {Mathematica Japonica}, volume = {52}, number = {3}, year = {2000}, pages = {345--358}, issn = {0025-5513}, mrnumber = {1796651}, mrclass = {03E35 (03E05 03E55 03G05 06E05)}, note = {\href{https://arxiv.org/abs/math/9903116}{arXiv: math/9903116}}, arxiv_number = {math/9903116} }