We give sufficient and necessary conditions to be fulfilled by a filter $\Psi $ and an ideal $\Lambda $ in order that the $\Psi $-quotient space of the $\Lambda $-ideal product space preserves $T_k$-properties ($k=0,1,2,3,3\frac{1}{2}$) (``in the sense of the \L os theorem''). Tychonoff products, box products and ultraproducts appear as special cases of the general construction.
@article{118543, author = {Milan Z. Grulovi\'c and Milo\v s S. Kurili\'c}, title = {On the preservation of separation axioms in products}, journal = {Commentationes Mathematicae Universitatis Carolinae}, volume = {33}, year = {1992}, pages = {713-721}, zbl = {0786.54009}, mrnumber = {1240193}, language = {en}, url = {http://dml.mathdoc.fr/item/118543} }
Grulović, Milan Z.; Kurilić, Miloš S. On the preservation of separation axioms in products. Commentationes Mathematicae Universitatis Carolinae, Tome 33 (1992) pp. 713-721. http://gdmltest.u-ga.fr/item/118543/
Ultraproducts in topology, Gen. Topology Appl. 7 (1977), 283-308. (1977) | MR 0458351 | Zbl 0364.54005
The box product of countably many metrizable spaces need not be normal, Fundamenta Mathematicae LXXXVIII.2 (1975), 127-132. (1975) | MR 0385781
General Topology, PWN - Polish Scientific Publishers, 1977. | MR 0500780 | Zbl 0684.54001
General Topology, Springer Verlag, Graduate Texts in Mathematics 27.
Box topologies, Quart. J. Math. Oxford 15 (1964), 41-54. (1964) | MR 0160184 | Zbl 0122.17404