Refactor satisfiability to independent set reduction

[GiggleLiu]

No description provided.

[GiggleLiu]

@SciCodePhy I refactored the code a bit, please make sure all the changes are correct.

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 93.54%. Comparing base (b90737a) to head (ae9768f).
Report is 2 commits behind head on main.

Additional details and impacted files

@@            Coverage Diff             @@
##             main      #80      +/-   ##
==========================================
- Coverage   93.81%   93.54%   -0.27%     
==========================================
  Files          30       30              
  Lines        1244     1177      -67     
==========================================
- Hits         1167     1101      -66     
+ Misses         77       76       -1     

☔ View full report in Codecov by Sentry.
📢 Have feedback on the report? Share it here.

[SciCodePhy]

@SciCodePhy I refactored the code a bit, please make sure all the changes are correct.

@GiggleLiu I implemented similar things on another branch and implemented the extract_multiple_solutions (not pushed yet), so I will integrate my code into this PR.

Besides, I think it might be better to assign random Bool values to missed literals in the assignment rather than assigning false to all the missed literals. I will modify this part.

The "extract_multiple_solutions" will be moved to another PR.

[SciCodePhy]

Implemented:

• Stable return for evaluate function of IndependentSet problem;
• Modify the refactored extract_solution for "SAT => Independent Set" reduction;
• Include "extract_multiple_solutions" function for "SAT => Independent Set" reduction;

Next Step:

• "extract_multiple_solutions" function will be included for other reductions.