Ciphertext notation where the ciphertext consists of two parts I've see in several places (here or there) the notation $c = (U, V)$ or $c =\langle U, V \rangle$, where $c$ is a ciphertext (to be transmitted).

But as both $U$ and $V$ are "key-like". I can't find if the key to be used on the other is $U$ or $V$.

From the context, I guessed it means "Encrypt $V$ with $U$ (ie the key) to produce $c$".

Can anyone confirm me this ? They are quite commons notations, but I can't find their meaning.
$c = (U,V)$ means that the ciphertext is actually a tuple, made of two parts, $U$ and $V$. It is very common to have ciphertexts that are actually tuples of elements. In this particular case, this scheme is reminiscent to Hashed ElGamal, where ciphertexts are composed of two parts: $U$, which essentially encodes the randomness used, and $V$, which contains the message XORed with a hashed value. 

Apart from that, note that, in general, a ciphertext never includes the key...otherwise, they would be trivially decrypted. The key or keys needed for decryption are separate values, and must be kept secret by the intended recipient of the ciphertext.