Partial order question, is reflexivity implied

Question

I have a question whether below sets of relationship are partial order?

a≤b, b≤c, c≤d

I wonder whether reflexivity is implied or not. What would you answer to above question, without any extra information?

Answer 1

Even if reflexivity was implied, transitivity is not true for that relation. Of course, transivity might also be implied, then you got a linear ordering of 4 elements.

Answering "no" would be the best idea, IMO, because without further info, it's best not to assume anything.