With Release 8.0 or later of GEMPACK, it is easy to model quotas, tariff rate quotas (TRQs) and other complementarities or inequalities explicitly.
For details and many worked examples, see here
The methods used to model quotas explicitly in GEMPACK were developed originally by Mark Horridge.
Prior to Release 8.0, special techniques were required. These techniques, which are no longer necessary, are described in two GTAP Technical papers and associated examples. In particular, it is no longer necessary to use TRQmate (supplied with GTAP Technical Paper number 18), nor is it necessary to explicitly run the approximate and accurate runs separately. This is all automated with Release 8.0 or later of GEMPACK.
We make these papers and examples available partly for historical reasons and partly because the associated examples and applications in the papers are still interesting.
There were errors relating to quota rents with TRQs in the December 2000 and April 2005 versions of GTAP Technical Paper 18. These errors are corrected in the July 2005 version.
You can run tariff-rate quota applications under RunGTAP - see for advice.
You can download GTAP-OQ.ZIP. This contains an implementation of production (output) quotas with the GTAP model. See NOTES.TXT in GTAP-OQ.ZIP for some details about the TAB file GTAP-OQ.TAB and simulations supplied. This implementation uses GEMPACK Complementarity statements. You should be able to add the module supplied to any more recent version of GTAP.TAB
GTAP Technical Paper no. 4:
"Implementing Quotas in GTAP using GEMPACK - or How to Linearize an Inequality"
by C. Bach and K. Pearson (GTAP Technical Paper number 4, November 1996)
describes the old methods for implementing explicit export or import quotas in models solved using GEMPACK. The paper also contains information about the old ways of implementing other inequalities in models.
Technical Paper (PDF file) [save this as file TP-4.PDF] (120K)
Accompanying the technical paper are hands-on examples.
Quota examples [save this as file QUOTA-EX.ZIP] (90K)
Appendix 1 of the above Technical Paper has details about these files.
If you are using the Demonstration Version of GEMPACK to work through the examples in the technical paper, you will also need to download
file XQ-TG.ZIP (550K) and file IQ-TG.ZIP (550K) [see Appendix 1 of the
technical paper].
GTAP Technical Paper No. 18:
"Implementing Bilateral Tariff Rate Quotas in GTAP using GEMPACK"
by Aziz Elbehri and Ken Pearson, December 2000, Revised April 2005, Second Revision July 2005
describes in detail the old methods for implementing Tariff Rate Quotas in the GTAP model. The methods described there could be applied to any model implemented using GEMPACK.
Technical Paper (PDF file) [save this as file TP-18.PDF] (410K)
There were errors relating to quota rents with TRQs in the December 2000 and April 2005 versions of GTAP Technical Paper 18. These errors are corrected in the July 2005 version.
Accompanying the technical paper are hands-on examples.
TRQ examples [save this as file TRQ-EX.ZIP] (400K)
Section 6 of the above Technical Paper has details about these files.