Constraints in P6

Dave,

Have you checked the little boxes to the left of the "Started" and "finished" dates on your status tab?

Hi Dave

Why do you want to "Hold" dates in your schedule?

It affects the critical path and causes negative float - all bad planning.

Best regards

Mike Testro

Mike,

I agree with you.

There is no need to fool CPM math to show criticality under date constraints. If the date constraint break logic then logic dates shall prevail. This is how Spider applies date constraints, shows criticality without breaking logic. A very simple concept, well kind of after you see the dog balls you know is a male dog. It is about correct mathematical modeling.

In Operations Research, a science of British origin similar to Newton Calculus, if you have a Linear Programming problem you have multiple constraints that must be satisfied, the correct solution shall stisfy all constraints. In scheduling you migh have date constraints but you also got logic, and logic is the mother of all constraints. Good scheduling consider all constraints.

Best regards,

Rafael

From Dave's original post, it sounds like he is trying to "hold" dates which are prior to the data date.

This would not be done by applying a constraint, but by applying actual dates -this is done by ticking the boxes to the left of the started & finished dates

Dave: P6 (correctly) will not allow any activities to have start or finish dates before the data date, unless you have told P6 that the activity has been started or completed, respectively. You do this by ticking the little boxes next to the "start" and "finish" dates.

I think you're proably use to MS Project, which allows for such abhorrences. P6 doesn't.

Cheers,

G