Systems, devices and techniques for soft-in, soft-out (SISO) decoding can include accessing initial soft information on a series of data units received over a communication channel, using a cyclic graphical model to represent a coding scheme associated with the received data units, obtaining cycle-free graphical models for a plurality of second conditions allowable by the coding scheme, and generating soft-out decision information by using information that includes the obtained cycle-free graphical models and the initial soft information. The number of obtained cycle-free graphical models can be less than a total number of conditions associated with the cyclic graphical model. Soft decision information can include confidence levels for each data unit.