Strong lensing in multimessenger astronomy as a test of the equivalence
  principle
  Standard Shapiro delay-based test of the equivalence principle, which are
grounded on the measurement of two arrival times from a unique source but from
messengers with different properties, cannot produce a reliable quantitative
test of the Einstein equivalence principle. Essentially because they are based
on the estimation for different messengers of the one-way propagation time
between the emission and the observation that is not an observable per se. As a
consequence, such tests are extremely model dependent, at best. In what
follows, I argue that the differential arrival times for strongly lensed
multimessengers can be used to define a new test of the Einstein equivalence
principle that is both well-defined from a relativistic point of view and model
independent---because it is entirely based on actual observables.
