Could you explain this code written in Jspin for Error diagnostic provided by SMV

ification AG AF (!request [o] & request [i] &Irequ... false as demonstrated by the following execution sequence -- state 1.1: cabin # 0 dir up request [o] 0 request (1]-0 request [2]-0 request [3] 0 - loop starts here - state 1.2: cabin1 request [3]1 state 1.3: cabin 2 state 1.4: cabin 3 dir down request [2] -1 request [3] state 1.5: cabin 2 request [2] 0 request [3]-1 state 1.6: cabin 1 state 1.7: cabin = 0 dir up state 1.8: cabin 1 Fig. 12.2. Error diagnostic provided by SMv