or clustered relays) and can always be decoded at the affected nodes; this decoded IRI is exploited in a superposition coding scheme that significantly improves the diversity-multiplexing tradeoff (DMT) performance of the system. On the other hand, relay selection has been introduced as a promising practical solution that achieves full diversity by keeping the implementation complexity low. In earlier works in which relays were assumed to lack data buffers, relay selection was mainly based on the max-min criterion and its variations (see, for example, [@BLE; @KAR; @KRI_minmax; @BLE1] and references therein). As a result, based on either proactive or reactive criteria, the relay that received the source signal is the same with the one that is subsequently forwarding the signal towards the destination.

In the adoption of buffer-aided relays, this coupling is broken as different relays could be selected for transmission and reception. Buffering at the relay nodes is a promising solution for cooperative networks and motivates the investigation of new protocols and transmission schemes. Ikhlef *et al.* [@IKH2] propose a novel criterion based on the $\max-\max$ Relay Selection (MMRS), in which the relay with the best Source-Relay (SR) link is selected for reception and the relay with the best 