It is proved that for a Baire space $X,$ a metrizable compact $Y,$ a metrizable space $Z$ and a compact-valued mapping $F: X × Y ⊸ Z$ which is lower semi-continuous with respect the first variable and continuous with respect to the second variable there exists a dense $G_δ$-set $A ⊆ X$ such that the restriction $F|_{A × Y}$ is continuous. It is constructed an example of a mapping $F : [0,1]^2 ⊸ [0,1]$ which is lower semi-continuous with respect the first variable, continuous with respect to the second variable and jointly discontinuous at every point of the set $[0,1] × \{0\}$.
[1] Baire R. Sur les functions des variables retlles // An. Mat. Pura Appl., ser. 3. – 1899. – 3 . – P.1-123.
[2] Breckenridge J.C., Nishiura T. Partial continuity, quasicontinuity and Baire spaces // Bull.Inst.Acad.Sinica.–1976.– 4 ,№2.–191-203.
[3] Colbrix J., Troallic J.P. Aplications separement continues // C.R. Acad. Sc. Paris Sec. A. – 1979. – 288 . – P. 647-648.
[4] Debs G. Points de continuitt d’une function stpartment continue // Proc. Amer Math Soc. – 1986. – 97 , №1. – P.167-176.
[5] Kozhukar O.G., Maslyuchenko V.K. Around Debs' theorem on multivalued mappings // Scientific Bulletin of Chernivtsi Univ. Mathematics. - 2004.- B.191-192.- P.61-66.
[6] V.K.Maslyuchenko, V.V.Mykhailyuk, O.G.Fotiy. Connections between different and aggregate properties of multivalued mappings // Mat. Studies. - 2011. - 35, №1. - P.106-112.
[7] Namioka I. Separate contimuty and joint continuity // Pacif.J.Math. – 1974. – 51 , №2. – P.515-531.
[8] Engelking R. General Topology. M.: Mir, 1986. - 752 p.
[9] Shouchan Hu., Papageorgion N. Handbook of Multivalued Analysis. Theory // Dordrecht / Boston/ London: Kluwer Academic Pablishens. 1997. – 964 p.
- ACS Style
- Beley , T.I.; Mykhaylyuk, V. Aggregate properties of multivalued mappings. Bukovinian Mathematical Journal. 2016, 2
- AMA Style
- Beley TI, Mykhaylyuk V. Aggregate properties of multivalued mappings. Bukovinian Mathematical Journal. 2016; 2(2-3).
- Chicago/Turabian Style
- T. I. Beley , Volodymyr Mykhaylyuk. 2016. "Aggregate properties of multivalued mappings". Bukovinian Mathematical Journal. 2 no. 2-3.