Dear all,
It has emerged that a bug appears in GAMS versions 24.5, 24.6, and 24.7, affecting the pre-processing of TIMES models in such a way that the models may be quite incorrectly formulated. There are mitigating factors, namely, if the modeller makes sure that the model never has any domain violations. However, having seen a large number of TIMES models, domain violations currently appear to be a very common occurrence in TIMES models, as such input data can be rather easily passed through by the VEDA user shell.
Therefore, users of the ETSAP TIMES model generator are advised to check their GAMS version, and if they are currently using one of the versions mentioned above, they should best either upgrade to a newer version (their licence permitting), or downgrade to an earlier version (for example, v24.4, which is not affected). For downloading different GAMS versions, visit: https://www.gams.com/download-old/ or for the latest: https://www.gams.com/download/
However, downloading GAMS v28.1 is not recommended either, due to another issue identified in that version.
I am sorry for any inconvenience this GAMS issue may have caused to modelers, and for the late discovery.
It has emerged that a bug appears in GAMS versions 24.5, 24.6, and 24.7, affecting the pre-processing of TIMES models in such a way that the models may be quite incorrectly formulated. There are mitigating factors, namely, if the modeller makes sure that the model never has any domain violations. However, having seen a large number of TIMES models, domain violations currently appear to be a very common occurrence in TIMES models, as such input data can be rather easily passed through by the VEDA user shell.
Therefore, users of the ETSAP TIMES model generator are advised to check their GAMS version, and if they are currently using one of the versions mentioned above, they should best either upgrade to a newer version (their licence permitting), or downgrade to an earlier version (for example, v24.4, which is not affected). For downloading different GAMS versions, visit: https://www.gams.com/download-old/ or for the latest: https://www.gams.com/download/
However, downloading GAMS v28.1 is not recommended either, due to another issue identified in that version.
I am sorry for any inconvenience this GAMS issue may have caused to modelers, and for the late discovery.