GATE CS 2017 Set 2 — Question 21
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Engineering Mathematics → Sets & Combinatorics → Partial Orders & Lattices
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Question
Consider the set under the partial ordering
.
The Hasse diagram of the partial order is shown below.
The minimum number of ordered pairs that need to be added to to make a lattice is ______.
.
The Hasse diagram of the partial order is shown below.
Correct answer
0.01 to 0.01
Solution
A lattice is a partially ordered set (poset) in which every pair of elements has a unique least upper bound (LUB) and a unique greatest lower bound (GLB).Let's analyze the given poset with and the relation :
1.Bottom and Top Elements: is the bottom element ( for all ) and is the top element ( for all ).
2.Incomparable Pairs: The pairs of elements that are not related are and .
3.Check for LUB and GLB:
- For the pair :
- Upper bounds: (since and ). The least upper bound is .
- Lower bounds: (since and ). The greatest lower bound is .
- For the pair :
- Upper bounds: (since and ). The least upper bound is .
- Lower bounds: (since and ). The greatest lower bound is .
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