Source: Real Anal. Exchange Volume 25, Number 2
(1999), 647-652.
In this article we present a condition on the sections $f^y$ of a function $f:
\mathbb{R}^2 \to \mathbb{R}$ having Lebesgue measurable sections $f_x$ and
quasicontinuous sections $f^y$ which implies the measurability of $f$. This
condition is more general than the Baire$^{**}_1$ property introduced by R.
Pawlak in [7]. Some examples of quasicontinuous functions satisfying this
condition and discontinuous on the sets of positive measure are given.
References
A. M. Bruckner, Differentiation of real functions, Lectures Notes in Math. 659, Springer-Verlag, Berlin 1978.
Mathematical Reviews (MathSciNet):
MR507448
R. O. Davies, Approximate continuity implies measurability, Math. Proc. Camb. Philos. Soc. 73 (1973), 461–465.
Mathematical Reviews (MathSciNet):
MR325870
Z. Grande, On strong quasi-continuity of functions of two variables, Real Anal. Exch., 21 (1995–96), 236–243.
Z. Grande, Un théorème sur la mesurabilité des fonctions de deux variables, Acta Math. Hung. 41 (1983), 89–91.
Mathematical Reviews (MathSciNet):
MR704527
S. Kempisty, Sur les fonctions quasi-continues, Fund. Math. 19 (1932), 184–197.
T. Neubrunn, Quasi-continuity, Real Anal. Exchange 14 (1988-89), 259–306.
Mathematical Reviews (MathSciNet):
MR995972
R. Pawlak, On some class of functions intermediate between the family of continuous functions and the class ${\cal B}^*_1$, Abstract of $15^{th}$ Summer School on Real Functions Theory, Liptovský Ján, Slovakia, September 6–11, 1998.
S. Saks, Theory of the integral, Warsaw 1937.
W. Sierpiński, Sur un problème concernant les ensembles mesurables superficiellement, Fund. Math. 1 (1920), 112–115.
F. D. Tall, The density topology, Pacific J. Math. 62 (1976), 275–284.
Mathematical Reviews (MathSciNet):
MR419709