18. Subsequence Existence
The chapter explores key mathematical principles related to sequences, particularly subsequences that are either strictly increasing or strictly decreasing. It utilizes various mathematical tools, including the pigeonhole principle, to demonstrate the existence of such subsequences in any arbitrary sequence of distinct real numbers. The chapter also delves into problems involving subsets and age groups, highlighting the application of these principles in real-world scenarios.
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Sections
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What we have learnt
- A sequence with distinct real numbers always contains a subsequence that is either strictly increasing or strictly decreasing.
- The pigeonhole principle can be effectively applied in problems to show the existence of specific groupings or properties.
- Mathematical proofs can be constructed through contradiction to establish the validity of statements about sequences and subsets.
Key Concepts
- -- Increasing Sequence
- A sequence of the form (a1, a2, ...) where a1 < a2 < a3 < ... < an.
- -- Decreasing Sequence
- A sequence of the form (a1, a2, ...) where a1 > a2 > a3 > ... > an.
- -- Subsequence
- A derived sequence that may not consist of consecutive elements from the original sequence.
- -- Pigeonhole Principle
- A principle stating that if there are more items than containers, at least one container must contain more than one item.
Additional Learning Materials
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