The two main types of linking clauses are "if _ then _", and "because _ therefore _". In most languages, these expressions don't distinguish between the different types of relationships they can imply, including causation and deduction. For example, "If you do X, Y will happen" (meaning that X will cause Y) is a different meaning from "If you do X, that entails that Y will happen" (X might not be the cause of Y, but that it happens gives us grounds to believe Y will happen). Spem distinguishes these different relationships:
ye- if. Used for any type of relationship. yei- because. (Takes the place of yewhen the premise is known to be true.) yeiis not strictly necessary, since a premise clause without yealready means it's true, but it exists for clarity. If the premise is long, it can be useful to have a way to signal from the start from that it's a preface to something else. zo- causation. ko- entailment. θo- entailment by definition. Note that the difference between this and kois that this one needs no other premises, while for non-definitional entailment, what's actually going on is that other premises are being used (since strictly speaking it's impossible to actually entail something without doing so by definition).