By definition, they are in parallel if and only if their respective terminals are tied together and nothing else is in the way. There is a more formal definition using topology but it's not very useful.
R1 is in parallel with R2: pin A of R1 is directly tied to pin A of R2, pin B of R1 is directly tied to pin B of R2;
R1 is not in parallel with R3: between pin A of R1 and pin A of R3 there is a battery and the K thingy (no idea of what that symbol mean).
Even if we reorder the circuit like this (Kirchoff says we can do it due to current law)
R1 is still not in parallel with R3 since even if one terminal is in common between them, between the other there still is the source and ammeter