difference of lattice elements
Let a,b∈𝔄. A of a and b is an element c∈𝔄 that b∩c=0 and a∪b=b∪c. When there is only one difference of a and b, it is denoted a∖b.
One immediate property is: 0 is the unique difference of any element a and itself (a∖a=0). For if c is such a difference, then a∩c=0 and a=a∪c. So c≤a by the second equation, and hence that c=a∩c=0 by the first equation.
For arbitrary lattices of two given elements do not necessarily exist. For some lattices there may be more than one difference of two given elements.
For a distributive lattice with bottom element 0, the difference of two elements, if it exists, must be unique. To see this, let c and d be two differences of a and b. Then
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b∩c=b∩d=0, and
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a∪b=b∪c=b∪d.
So c=c∩(b∪c)=c∩(b∪d)=(c∩b)∪(c∩d)=0∪(c∩d)=c∩d. Similarly, d=d∩c. As a result, c=c∩d=d∩c=d.
Title | difference of lattice elements |
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Canonical name | DifferenceOfLatticeElements |
Date of creation | 2013-03-22 17:57:44 |
Last modified on | 2013-03-22 17:57:44 |
Owner | porton (9363) |
Last modified by | porton (9363) |
Numerical id | 10 |
Author | porton (9363) |
Entry type | Definition |
Classification | msc 06B99 |
Related topic | ComplementedLattice |
Related topic | Pseudodifference |
Related topic | SectionallyComplementedLattice |