Hint Resolve trans_incl.
Hint Resolve comp_incl.
Hint Resolve union_incl.
Hint Resolve star_incl.
Hint Resolve plus_incl.
Hint Resolve trans_eeq.
Hint Resolve comp_eeq.
Hint Resolve union_eeq.
Hint Resolve star_eeq.
Hint Resolve plus_eeq.
Section InclEeq.
Variables X Y: Type.
Variables S R T: relation2 X Y.

Lemma plus_star_plus: forall y x z, plus R x y -> star R y z -> plus R x z.