Re: Planner-list predecessors for fixed date tasks

Hello Kurt,

If you want to change the start date on a task with a 'SF' relationship, you should assign a resource and adjust the resource units to something less than 100%.

problem : using resources this way turns it to nothing more than an 
abstract parameter.

Well, if you've set the finish date for task A with a SF or FF relationship, then we need to let the start date float

That's precisely the question : the finish date for task A is then _set 
and fixed_. both start date _and finish date_ for task A sould be floating
two rules can be imagined to define SF links :
 - end(A) < start(Deadline) ; that's the minimal constraint and so the 
more usefull (and generally the actual logical link).
 - end(A) = start(Deadline) ; that's the maximal constraint for an SF 
link, and the Planner's one. generally too restrictive.

the less restrictive is a tool, the more useful it is... and the more 
complex is the algorithm.


is there any way to centralize a collective analyze and specification 
for algorithm evolution ?
is there any conceptual documentation (exept code and its comments) for 
link rules and sheduling algorithm ?
I have no time (like everyone) but should be interessed (probably like 
some others) to contribute to a conceptual specification

Planner is no far away from being an excelent simple and intuitive tool 
but, to be honest, I'm not acheaving to use it efficiently at this time

Regards,
Ricardo FERNANDEZ


------------------------------------------------------------------------
*De : * Kurt Maute <[email protected]>
*Envoyé : * 29/10/2009 14:35:30 +0100
*À : * Ricardo Fernandez <ricardo.fernandez-/[email protected]>
*Copie : * pete davidson <[email protected]>, planner 
<[email protected]>
*Objet : * Planner-list predecessors for fixed date tasks

> On Wed, 2009-10-28 at 23:08 +0100, Ricardo Fernandez wrote:
>   
>> Hello Pete,
>>
>> I'm not sure to understand, but my comment could help.
>>
>> if you have a "Deadline" task  for a part of your project (including,
>> for exemple, task A)
>>  - you can set "Deadline" task as a fixed date milestone
>>  - of course you can't set any predecessor for this fixed date task
>>  - so you can't set A as predecessor (for example "end to start" link)
>> for "Deadline" task, but...
>>  - you can set "Deadline" task as predecessor (same example ; "start
>> to end" link) of A
>>
>>     
> Correct.  The way to set up this relationship is to edit your task A and
> set up the deadline as a predecessor with a 'SF' relationship.  Task A
> will then be scheduled so that it ends just prior to the deadline task.
>
>   
>> limits for this example :
>>  - even if A is an "as soon as possible" task, it will be scheduled to
>> "the last moment" before "Deadline". why ? we just wan't it to become
>> a "not after" task.
>>     
>
> ASAP just means that the task start date will float based on predecessor
> relationships.  Planner schedules all tasks (without assigned resources)
> assuming that a single resource will work at 100% capacity for the
> duration, and sets the start and end dates accordingly.  If you want to
> change the start date on a task with a 'SF' relationship, you should
> assign a resource and adjust the resource units to something less than
> 100%.
>
>   
>>  - you can't anticipate A setting it to fixed date (today for
>> example). why ?
>>     
>
> see above
>
>   
>>  - you can't set any other predecessor to A (a current task ending
>> tomorrow, linked "end to start", for example), even if A has been
>> scheduled on next year. why ?
>>
>>     
> Well, if you've set the finish date for task A with a SF or FF
> relationship, then we need to let the start date float in order for the
> scheduling algorithm to work.
>
> If you created a task B, you could set task A as a predecessor with a SF
> or FF relationship.  In this way, you're essentially scheduling from the
> deadline back to the present day.
>
>   
>> I agree that external constraints are decisive in project scheduling
>> and that Planner constraints rules are too much restrictive.
>> but it's not an easy problem, and coding realy accurate rules could be
>> an infinite task.
>>
>> so just try to use such links with parsimony 
>>
>> Regards,
>> Ricardo FERNANDEZ
>>
>>
>>
>> ______________________________________________________________________
>> De :  Alexandre Franke <[email protected]>
>> Envoyé :  25/10/2009 13:14:00 +0100
>> À :  planner <[email protected]>
>> Objet :  Planner-list predecessors for fixed date tasks
>>
>>     
>>> On Sun, Oct 25, 2009 at 5:42 AM, pete davidson <[email protected]> wrote:
>>>   
>>>       
>>>> Hi all
>>>>     
>>>>         
>>> Hi,
>>>
>>>   
>>>       
>>>> I'm trying to use Planner to manage academic grant applications.  As such,
>>>> there's a number of key tasks whose dates are externally set and
>>>> non-negotiable (such as the date the grant must be submitted to the funding
>>>> agency, or the date a letter of intent is due to the funding agency).  I've
>>>> been 'locking' these dates by creating a milestone task (eg "Submit grant")
>>>> with a schedule of 'on fixed date' on the required date.
>>>>
>>>> The problem I'm having is when I try and link these milestone tasks to the
>>>> rest of the tasks in the project by setting a predecessor.  This produces
>>>> the error "You cannot add a relationship to a task with a Must Start On
>>>> constraint."  I've also tried using a one-day task instead of a milestone
>>>> task, but get the same error.
>>>>     
>>>>         
>>> The problem here is with the meaning of the predecessor relationship.
>>> If you set A as a predecessor of B, it means that you cannot start
>>> working on B until A is done. So what would happen if you start A on
>>> oct 26th, need 4 days to finish it and set B on oct 28th (fixed date)?
>>> That wouldn't make any sense because you'd need to work on B but you
>>> couldn't since A isn't done yet.
>>>
>>> This has nothing to do with the fact that it's a milestone.
>>>
>>>   
>>>       
>>>> Is there another approach to dealing with externally set fixed dates that
>>>> I'm missing, or a way to set milestone tasks which allows linking to other
>>>> tasks?
>>>>     
>>>>         
>>> You can do it without the predecessor relationship, I think it's the
>>> way that would make the most sense.
>>>
>>>   
>>>       
>> _______________________________________________
>> Planner-list mailing list
>> [email protected]
>> http://mail.gnome.org/mailman/listinfo/planner-list
>>     
>
>
>
>

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