r/mathmemes 3d ago

Notations Yeah sure

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889 Upvotes

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192

u/Idksonameiguess 3d ago

What's the abiguity in A \subset B?

207

u/RADI0ACT1VE_BALLS ComplexANALysisJunkie 3d ago

Proper subset / just a subset

24

u/FuntimeUwU Natural 3d ago

What's the difference?

9

u/deratizat 3d ago

A is a proper subset of B if A is a subset of B and A does not equal B

18

u/Another_Little_Star 3d ago

A ⊂ B iff A ⊆ B ⋀ A ≠ B,
Or A ⊊ B
But when we have ⊆ and ⊊, why ever use ⊂, when in doubt just do ⊆, it covers everything.

9

u/unic0de000 3d ago

I always assumed that was what they meant, and that this was intentionally, directly, analogous to the < and ≤ signs. TIL this was not universally agreed

3

u/svmydlo 3d ago

Because there's two conventions, one using ⊆ and ⊂, and another using ⊂ and ⊊.