Upper bounds to error probability with feedback

A new analysis technique is suggested for bounding the error probability of fixed length block codes with feedback on discrete memoryless channels from above. Error analysis is inspired by Gallager´s error analysis for block codes without feedback. Using Burnashev-Zigangirov-D´yachkov encoding scheme analysis recovers previously known best results on binary symmetric channels and improves up on the previously known best results on k-ary symmetric channels and binary input channels.