Semistable reduction for overconvergent F-isocrystals, II: A   valuation-theoretic approach
  We introduce a valuation-theoretic approach to the problem of semistable reduction (i.e., existence of logarithmic extensions on suitable covers) of overconvergent isocrystals with Frobenius structure. The key tool is the quasicompactness of the Riemann-Zariski space associated to the function field of a variety. 
Kiran S. Kedlaya