  Based on conformal symmetry we propose an exact formula for the four-point
connectivities of FK clusters in the critical Ising model when the four points
are anchored to the boundary. The explicit solution we found displays
logarithmic singularities. We check our prediction using Monte Carlo
simulations on a triangular lattice, showing excellent agreement. Our findings
could shed further light on the formidable task of the characterization of
Logarithmic Conformal Field Theories and on their relevance in physics.
