Ch 12 Reloop, an Algebra-Based Query Language for O2 - 1 Introduction - 2 An Example - 3 Design Issues - 4 The Reloop Language - 5 Reloop Semantics through an Algebra - 6 Translation from Reloop to CO2 - 7 Conclusion - 8 Acknowledgements References Appendix: Construction of the Algebraic Macro-Operators