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I am looking for following symbols:

Total Relation: <<->
Surjective Relation: <->>
Total surjective Relation: <<->>

This is the sort of thing I’m looking for (source):

enter image description here

Can anybody help me?

Thanks in advance.

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Can you point to some source showing the symbols you're after? – egreg Feb 4 '14 at 10:29 Relations (5.4 - 5.6) – Philip Errichte-Es Feb 4 '14 at 10:35
Welcome to TeX.SX! You can have a look at our starter guide to familiarize yourself further with our format. You should start by seeing whether leads you to the correct symbols. – Andrew Swann Feb 4 '14 at 10:37
I guess that they are using a trick, a kind of two arrows with negative space. – Sigur Feb 4 '14 at 10:39
@egreg, the arrow tips from amssymb does not match with the default arrow tips (compare $S\mathrel{\parbox[b]{0pt}{$\twoheadleftarrow$}\rightarrow }T$). – Sigur Feb 4 '14 at 10:50

2 Answers 2

up vote 14 down vote accepted

Here's a way to build symbols like in the document you link to:



$A\rel B\trel C\srel D\tsrel E$


You can see that they all have the same width.

enter image description here

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Thank you very much. Exactly what I was searching for. – Philip Errichte-Es Feb 4 '14 at 12:02

Is this what you want?

$\ll \gg$ 

enter image description here

Or this (from amssymb):

$\twoheadleftarrow \twoheadrightarrow \rightarrowtail \leftarrowtail$

enter image description here

share|improve this answer
The second examples (\twoheadleftarrow,...) needs an > on the right side. – Philip Errichte-Es Feb 4 '14 at 10:33

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