F(A, B, C, D) = ∑ (1, 2)

Term 1 (Binary ‘0001’): A̅ . B̅ . C̅ . D

Term 2 (Binary ‘0010’): A̅ . B̅ . C . D̅

The function F will be the logical OR of these terms:

F(A, B, C, D) = (A̅ . B̅ . C̅ . D) + (A̅ . B̅ . C . D̅)

```
library IEEE;
use IEEE.STD_LOGIC_1164.ALL;
-- Entity declaration
entity 1fFunction is
port (
A, B, C, D : in std_logic; -- Input signals A, B, C, D
F : out std_logic -- Output signal F
);
end entity 1fFunction;
-- Architecture
architecture Con_Logic_Arch of 1fFunction is
begin
-- Concurrent signal assignment implementing F(A, B, C, D) = Σ(1, 2)
F < = (not A and not B and not C and D) or -- term 1 (0001)
(not A and not B and C and not D); -- term 2 (0010)
end architecture Con_Logic_Arch;
```