features

Checkers Features (in progress) 

Sources looked at:
https://pdfs.semanticscholar.org/91c9/d140267f3b008d00b330b6b0e9182fa4b62e.pdf
http://www.cs.huji.ac.il/~ai/projects/old/English-Draughts.pdf

Some features to consider for the Evaluation Fuction, these can be used
as parameters, we need to decide which features we want to use and which ones
are more important than others. We can't consider all of these in our function
as it would take too much time.

Basic features

1. Number of Pawns
2. Number of Kings
3. Number of safe pawns - ones on the sides of the board that can't be captured
4. Number of safe kings
5. Number of moveable pawns - moves other than capture
6. Number of moveable kings - moves other than capture
7. Aggregated distance of the pawns to promotion line (total distance of all the pawns)
8. Number of unoccupied spots on promotion line 

**Kings would obviously have a greater weight than pawns becuase they are more valuable.
If pawns value = 1, we could make king = 2

Some more features to consider

9.  Number of "defender" pieces (located in the lowermost 2 rows)
10. Number of "attacking" pieces (located in the topmost 3 rows)
11. Number of central pieces (located on the eight central squares of the board)
12. Number of central kings
13. Number of pawns on main diagonal
14. Number of kings on main diagonal
15. Number of pawns of double diagonal
16. Number of kings on double diagonal 
17. Number of "loner" pawns - not adjacent to any other pawn
18. Number of "loner" kings
19. Number of holes - empty squares adjacent to at least 3 pieces of the same color

Some weird patterns to consider

19. Triangle Pattern
20. Oreo Pattern
22. Bridge Pattern
23. Dog Pattern
24. Pawn in Corner 
25. King in Corner

**The paper didn't do a great job describing these patterns, still not really
sure what the oreo and dog one is, there is a picture if you go to the first link

Phases of the Evaluation - We can change our evaluation one time

3 stages to consider:
1. Beginning - each player has more than 3 pawns and no kings present
2. Kings - each player has at least 3 pieces left and there is at least
one king present
3. End - one player less than or equal to 3 pieces left on the board

**We only get to change one time, so we need to decide where the change will 
be, and what will trigger the change. We can pick one of these places or
make up our own, it seems it would be better to have a beginning/middle stage and 
then end stage