www.company.com module code ma1032n: logic lecture for week 6 2012-2013 autumn

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www.company.com

Module Code MA1032N:Logic

Lecture for Week 6

2012-2013 Autumn

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AgendaWeek 6 Lecture coverage:

– Power Set

– Cartesian Product

– Partitions

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Power Set

The set whose elements consist of all the

subsets of a given set A is called the power set

of A.

This set is written P(A).

Thus P(A) = {X:X  ⊆ A }

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Power Set (Cont.)

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Power Set (Cont.)

Example:

So If B = 2 then P(B) = 4 =22

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Power Set (Cont.)

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Power Set (Cont.)

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Power Set (Cont.)

Theorem 2

A set containing n distinct elements has 2n subsets

More formally:

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The Cartesian Product of Two Sets

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The Cartesian Product of Two Sets(Cont.)

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The Cartesian Product of Two Sets(Cont.)

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Partitions

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Partitions (Cont.)

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Set Partition

A

WX Y

In this diagram, the set A (the rectangle) is partitioned into sets W,X, and Y.

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Partitions (Cont.)

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Partitions (Cont.)

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Partitions (Cont.)

We implied in our definition of partition that the

number of blocks in a partition is finite.

A more general definition would allow for an infinite

number of blocks, although we will not be

concerned with these. However:

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