I am currently studying for my exam in theoretical CS. In my lecture notes it says:
L1 ∪ L2 is semi decidable if L1 and L2 are semi decidable languages.
I want to proof the statement above for practice purposes. At this point, however, I am fairly clueless. Which technique could I use to proof that statement (maybe reduction?, or construct a Turing machine?). Thank you so much in advance.