(motive : Option (Option Lean.Elab.DecreasingBy × Subarray (Option Lean.Elab.DecreasingBy)) → Sort u_1) →
  (x : Option (Option Lean.Elab.DecreasingBy × Subarray (Option Lean.Elab.DecreasingBy))) →
    (Unit → motive none) →
      ((decrTactic? : Option Lean.Elab.DecreasingBy) →
          (s' : Subarray (Option Lean.Elab.DecreasingBy)) → motive (some (decrTactic?, s'))) →
        motive x