a single line
one to one
a single line with 3 small lines at the right side
one to many
a single line with 3 small lines coming out of each sides
many to many
a single line with 3 small lines at the left side
many to one
a single line with 1 at one end and ∞ on the other side
one to many
a single line with ∞ at one end and 1 at the other
many to one