<p>I need to take either or next semester, and can’t really decide. Which subject is more important to learn?</p>
<p>It really depends on your interests.</p>
<p>If you plan on doing futher study into an applied area like cryptology, then abstract algebra would be the better choice. Then again, the design of networks and even network security can also use principles of graph theory.</p>
<p>If you are planning to get a Master’s/PhD in Mathematics, most programs want extra semesters in BOTH Algebra (abstract) and Analysis (Advanced Calculus, Real Analysis).</p>
<p>From a “used in more applied engineering/CS areas” standpoint?..Graph Theory</p>
<p>graph theory</p>