Leapfrog, adpatve stepsize, and time reversibility

[junpenglao]

@Hamster_on_wheels

Does the leapfrog step use adaptive step-size by default during both the tuning and sampling phases?

Nope, during sampling phase all tuning is off

@Hamster_on_wheels

Is the leapfrog step with adaptive step-size time-reversible?

within one HMC or NUTS step the step size is constant, so in that regard it is time-reversible still.