Upper bounds on |C2| for a uniquely decodable code pair (C1, C2) for a two-access binary adder channel

An algebraic and a combinatorial upper bound are derived on |C_{2}| given the code C_{1} , where (C_{l}, C_{2}) is a uniquely decodable code pair (C_{1}, C_{2}) for a two-access binary adder channel. A uniquely decodable code with rate pair (0.5170, 0.7814) is also described.