"If A then B" in Venn (or Euler) Diagrams How can I represent "If A then B" in a diagram?
I thought it would be a simple subset like $A ⊂ B$. However this material says that

If $A$ then $B$ $=$ $A^c ∪ B$.

Now I am confused.
You want to construct the set $\;\{x\mid x\in A \to x\in B\}\;$.

Then by implication equivalence this is $\;\{x\mid x\not\in A \vee x\in B\}\;$.

Which is simply $\;A^\complement \cup B\;$.

This is the set of all elements that, if they're in A then they're in B



The statement $A\subseteq B$ is not a set.  It is a relation.  It is the statement that $y\in A \implies y\in B$.

In the specific case that  $A$ is a subset of $B$, then there is no element that is not in $A^\complement \cup B$.



So if you wanted to represent the statement "if $A$ then $B$", you could have $A$ as a subset of $B$.

But if you wanted to represent all elements that "if in $A$ then in $B$" you would use the union: $A^\complement\cup B$.
It is quite simple - the external shape is B and A is fully included