To a correlation function in a two-dimensional conformal field theory with
the central charge c=1, we associate a matrix differential equation Ψ′=LΨ, where the Lax matrix L is a matrix square root of the
energy-momentum tensor. Then local conformal symmetry implies that the
differential equation is isomonodromic. This provides a justification for the
recently observed relation between four-point conformal blocks and solutions of
the Painlev\'e VI equation. This also provides a direct way to compute the
three-point function of Runkel-Watts theory -- the common c→1
limit of Minimal Models and Liouville theory.Comment: 20 pages, v3: Corrected sign mistakes in eqs. (4.35), (4.37), (4.42),
(4.45) and (4.52). Conclusions unchange