Identify the gate represented by the block diagram of Fig. Write its boolean expression, the truth table and name of the gate, it works.

`:|{:(A,B,A+B,bar(A+B)),(0,0,0,1),(1,0,0,1),(0,1,1,0),(1,1,1,0):}:|`

Explanation

The output of OR gate is made as input for NAND gate. Hence the Boolean expression for final output,
`y=bar((A+B).(A+B))=bar((A+B))+bar((A+B))`
`=bar((A+B))`. It is NOR gate.