### 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

### How to generate Golden Ratio by programming?

Golden ratio has been a fascinating topic for last more than 2400 years despite it does not have reliable evidence. Golden ratio is seen in the circle of Sunflower "flower". We can get golden ratio when we divide a line into two parts, the ratio of dividing the large part with small part is equal to the whole length divided by the longer part. For a programmer it will be more fascinating to know how to code the golden ratio. The most easy way to do this is by using Fibonacci Series. We can use python code like this. s = 0 a = 1 b = 1 for x in range(9999): c = a + b a = b print (c/b)  #This is the golden ratio b = c Golden ratio occurs in nature in different forms. Some of the examples are: 1. Flower Petals 2. Seed Heads 3. Pine Cones 4. Shells 5. Spiral galaxies 6. Hurricanes 7. Fingers 8. Animal Bodies 9. DNA molecules Thank you! A blog by Saroj Bhattarai

### Web Scraping using Beautiful Soup (NEPSE LIVE DATA SCRAPING IN PYTHON)

from  bs4  import  BeautifulSoup import  requests import  csv source = requests.get( "http://nepalstock.com.np/" ).text soup = BeautifulSoup(source,  'lxml' ) csv_file =  open ( 'nepse.csv' , 'w' ) csv_writer = csv.writer(csv_file) csv_writer.writerow([ 'Symbol' ,  'Values' ,  'Total Traded amount' ]) marquee_tag = soup.find(      'div' ,  class_ = "col-xs-10 col-md-10 col-sm-12" ).marquee.b for  span_tag  in  marquee_tag( 'span' ):     span_tag.replace_with( '' ) for  img_tag  in  marquee_tag( 'img' ):     img_tag.replace_with( '' ) symbol_list = marquee_tag.text.split( '( )' ) all_symbols = [] short_name = [] per_share_value = [] total_traded_amount = [] a1 = [] a2 = [] a3 = [] for  symbol  in  symbol_list:     symbol_name = symbol.replace( u ' \xa0 ' ,  u '' )     all_symbols.append(symbol_name) all_