### How to write PROLOG program for half adder?

In this problem, we are going to implement some logic (of course it is all about logic) that will run calculate the half adder sum and carry. We know has two inputs, and it will give sum and carry which looks like this:

X            Y                 Sum                 Carry
0            0                  0                      0
0            1                  1                      0
1            0                  1                      0
1            1                  0                      1

So, to implement sum we need XOR gate and to implement Carry we need AND gate.

Here is how we do it:

xORGate(0,0,0).
xORGate(0,0,0).
xORGate(0,0,0).
xORGate(0,0,0).

aNDGate(0,0,0).
aNDGate(0,0,0).
aNDGate(0,0,0).
aNDGate(0,0,0).

Now, you can run this code by giving the values of X and Y.
like this:
halfadder(1,1,S,C)  and the output will be
S=0
C=1

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1. The half adder adds two single binary digits A and B. It has two outputs, sum (S) and carry (C). The Boolean logic for the sum (in this case S) will be A′B + AB′ i.e X-OR whereas for the carry (C) will be AB i.e AND.

### Basic guidelines for Chess opening.

If you are reading this blog, you probably know how the pieces move in the game of chess.  The player with the white pieces always moves first. The opening is generally considered complete when your rooks are connected. There are some basic principles to follow how to play efficiently. We should focus on the development of pieces. Here are top 10 opening rules for good chess opening: We must attack the center of board. So,  OPEN  with a  CENTER PAWN like  e4, d4. While ( e4 ,  d4 ,  e5 ,  d5 ) are generally regarded as the central squares, the same principle can sometimes be extended to the adjacent squares like ( c4 ,  c5 ,  d3 ,  d6 ,  e3 ,  e6 ,  f4 ,  f5 ).      DEVELOP pieces with  threats .  Always develop your Knights before Bishops . Develop knights to towards the center of board rather than side of board. When the knight is developed in the center, it could attack up to 8 squares.  The real reason to  develop Knights before Bishops  is that Knight are shorter- range pie