This article outlines everything you need to know to work with logic ties in ALICE:

• Hard Logic vs. Soft Logic
• Precedence Relationships in ALICE
• How to Add/Remove Contained Relationships (in Bulk)
• How to add Predecessors and Successors
• How to Review Relationship Details

Hard Logic vs. Soft Logic

There are two types of logic ties: hard logic and soft logic (or preferential logic).

Hard logic, also known as mandatory dependencies, is based on physical or logical relationships that require one activity to be completed before another can begin. For example, excavation must be complete before drainage pipes can be installed. Hard logic is often based on contractually required items or physical limitations.

Soft logic, also known as preferential logic or discretionary dependencies, is based on best practices, preferences, resource availability, or your expert judgment. Soft logic allows for more flexibility, and the order of activities can be adjusted based on needs and priorities. For example, paving lane 1 before lane 2, or lane 2 before lane 1, or paving both at the same time are 3 different soft logic dependencies.

In ALICE, upon import of your schedule, all logic comes in as "hard logic." Using the different functionalities within ALICE, select soft logic can be removed to allow ALICE the flexibility to explore different options.

Precedence Relationships in ALICE

The dependencies between activities in a schedule are defined by precedence relationships. 
ALICE supports the 4 standard precedence types most commonly used in scheduling software: FS, SS, FF, and SF.

In addition, ALICE supports more strict precedence definitions that allow users an increased degree of control in defining dependencies. We call these ALICE custom precedence types. Read on to learn more.

Standard Precedence Types

The most common types of dependencies are the following four (4):

1. Finish-To-Start (FS): Activity B can begin after A is finished.

In other words: Finish A ≤ Start B

2. Start-To-Start (SS): Activity B can start at the same time as A.

In other words: Start A ≤ Start B

3. Finish-To-Finish (FF): Activity B can finish at the same time as A.

In other words: Finish A ≤ Finish B

4. Start-To-Finish (SF): Activity B can finish at the same time as A starts.

In other words: Start A ≤ Finish B

ALICE Custom Precedence Types

In ALICE, the above relationship types are extended by adding the "At" type, which imposes the type of dependency. Therefore, the additional precedency types are transformed to:

1. Finish - At - Start (FaS): Activity B must begin after A is finished.

Or: Finish A = Start B

2. Start - At - Start (SaS): Activity B must start at the same time as A.

Or: Start A = Start B

3. Finish - At - Finish (FaF): Activity B must finish at the same time as A finishes.

Or: Finish A = Finish B

4. Start - At - Finish (SaF): Activity B must finish at the same time as A starts.

Or: Start A = Finish B

Be mindful when using the custom precedence types, as they impose a very strict relationship between activities, which can render your schedule infeasible. 

How to Add/Remove Contained Relationships (in Bulk)

To add and remove logic ties in bulk, use the Removed Contained Relationships feature and the Add Contained Relationships feature. 

For a more hands-on experience, navigate through the player for an interactive walk-through, or if you prefer a more detailed approach, scroll down for a step-by-step guide:

Remove Contained Relationships (aka Common Relationships):

1. On the Gantt Chart on the Plan page, bulk select the tasks for which you want to remove the common relationships.
   • Check the box of the WBS summary to select all tasks within that WBS
2. Click on the Remove Contained Relationships icon on the upper-left side of the page
3. In the window, you can see the number of common relationships
4. Click on the arrow to review the details of each relationship
   • All common relationship arrows will be highlighted in RED color in the timeline view
5. Click Remove to complete the action.

Add Contained Relationships (aka Common Relationships):

1. On the Gantt Chart on the Plan page, bulk select the tasks you want to add to the common relationships.
   • Check the box of the WBS summary to select all tasks within that WBS
2. Click on the Add Contained Relationships icon on the upper-left side of the page
3. In the appeared window, select the category of relationships to add:
   • Predecessor
   • Successor
4. Check the task's boxes to add relationships to the initially selected tasks
5. Define the relationship type and lag: FS, SS, FF, SF, FaS, SaS, FaF, SaF 
6. Click Add Relationships to complete the action.

How to add Predecessors and Successors

Predecessors and successors can be added to the task(s) in two ways:

1. From the task list view
2. From the timeline (Gantt) view

For a more hands-on experience, navigate through the player for an interactive walk-through, or if you prefer a more detailed approach, scroll down for a step-by-step guide:

Add Predecessors & Successors from the task list:

1. On the Gantt Chart view on the Plan page, "right-click" on the task list or timeline view and select "Edit Columns."
2. Check the "Predecessors" and "Successors" boxes, and click Done to add the columns to the Gantt chart.
3. Double-click on the Predecessors or Successors cell to open the assignment window
4. To assign the relationships:
   1. Select one or multiple tasks or milestones by checking the boxes
   2. Select the Relationship Type and define the duration of the Lag 
   3. Click Save to complete the action
5. Click Re-Schedule to recalculate the schedule with new changes

Add Predecessors & Successors from the timeline view:

1. On the timeline view on the Plan page, hover the mouse courser on the activity bar to highlight the connection dots 
2. Click and hold the circle and drag it to connect to the beginning or end of the required task. 
3. Once connected, select the Relationship Type and define the duration Lag 
4. Click X to close the assignment window
5. Click Re-Schedule to recalculate the schedule with new changes

How to Review Relationship Details

Once the logic ties are adjusted, the relationship details can be reviewed for each activity.

For a more hands-on experience, navigate through the player for an interactive walk-through, or if you prefer a more detailed approach, scroll down for a step-by-step guide:

Review Relationship Details:

1. On the Gantt Chart of Analyze page, select a task to activate the Relationship Details
   • Once selected, the Relationship Details will appear at the bottom of the page
2. In the Relationship Details, users can review: 
   • Free and Total Slack
   • Predecessors and Successors 
   • Driving and Critical tasks
   • Reasons
     • Precedence is the standard relationship type defined by users such as FS, SS, FF, and SF.
     • Resource is the resource link generated by ALICE based on resource assignment. This applies to crews, equipment, materials, and milestones.
   • Time Gap is the duration or float associated with previous (predecessor) and subsequent (successor) activities.
   • Go to the previous (predecessors) or next (successor) of the selected task by clicking Select.