A characterization of the moonshine vertex operator algebra by means of   Virasoro frames
  In this article, we show that a framed vertex operator algebra V satisfying the conditions: (1) V is holomorphic (i.e., V is the only irreducible V-module); (2) V is of rank 24; and (3) V_1=0; is isomorphic to the moonshine vertex operator algebra constructed by Frenkel-Lepowsky-Meurman. 
Ching Hung Lam and Hiroshi Yamauchi