sufficiently heavy strange quarks there is a first-order phase transition, whereas below some threshold value there is only a crossover. A very specific, concrete, and achievable goal is to locate the critical strange quark mass, and to verify (or not) existing indications that the physical strange quark mass is subcritical. It is also important to quantify the differential strange quark contribution to pressure and density. This would be an interesting measure of how nearly free the quarks in the plasma are, and could provide a baseline for interpreting enhanced strangeness multiplicities observed in heavy ion collisions.

### Exploring Small $\mu/T$

Finite chemical potential has long been [*terra incognita*]{} for numerical simulation of QCD, because configuration by configuration the usual path integral for the partition function contains a complex phase, and there are big cancellations.

These cancellations are less severe for small $\mu/T$ and not too large volumes, and are absent for imaginary $\mu$. Exploration of these regimes has begun, but much more remains to be done, especially in working towards realistic quark masses and reliable error estimates. There is a potential connection to heavy ion experiments, where the effective chemical potential varies with rapidity.

Challenges
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### Locate the True 