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Mathematics
Combinatorics
1. Introduction to Combinatorics
2. Fundamental Counting Principles
3. Permutations
4. Combinations
5. The Binomial Theorem
6. Advanced Counting Techniques
7. Recurrence Relations
8. Generating Functions
9. Special Counting Numbers and Sequences
10. Graph Theory and Combinatorics
11. Design Theory
12. Probabilistic Combinatorics
13. Algebraic Combinatorics
14. Extremal Combinatorics
15. Applications and Advanced Topics
Permutations
Arrangements of Distinct Objects
Definition of Permutation
Full Permutations
Partial Permutations
The Formula P(n,k)
Relationship to Factorials
Permutations with Repetition
Definition and Examples
Multinomial Coefficients
Multinomial Formula
Applications to Word Arrangements
Circular Permutations
Definition and Properties
Linear vs. Circular Arrangements
Formula for Circular Permutations
Rotational Symmetry
Necklace Problems
Derangements
Definition and Motivation
Basic Examples
The Subfactorial Notation
Recurrence Relation for Derangements
Inclusion-Exclusion Formula
Asymptotic Behavior
Applications of Derangements
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2. Fundamental Counting Principles
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4. Combinations