# Tag Info

Accepted

### Uses of quasi-PERs/difunctional relations/zig-zag relations?

Makoto Takeyama and I sent the following to data-refinement@etl.go.jp on Jan 5, 1996: Subject: what is a data refinement relation? Dear all: anyone still interested in data refinement? ...
• 196
Accepted

### Why Reflexive Graphs for Parametricity?

In the months since I asked this question, I think I have found a sensible answer. Often, the type of relations considered do not compose. For instance, if your notion of a relation $R : D \to E$ ...
• 1,474