Network diagram in trading example. How to build a network graph in Excel (Excel)
Example 1. The project includes the following works presented in the table. Build a network schedule for the implementation of a set of works.
Decision. Work a 1 and a 2 is not preceded by any work, therefore, on the graph they are depicted by arcs coming out of the initiating event (1), which means the moment the project is started. work a 3 work precedes a 1 , so on the graph the arc a 3 directly follows the arc a one . Event (2) means the end of the work a 1 and the commencement of the works to which it precedes. work a 4 predate work a 1 and a 2. On the graph, this dependence is reflected by introducing a fictitious work (2, 3). The moment of completion of the event (3) will be the moment by which the work will be completed a 1 and a 2 and work can begin a 4 . Similarly, taking into account the relationships, all other works are shown on the graph. The final event (6) means the moment of completion of the entire project.
The rules used in building a network graph.
1) there should be no “dead ends” in network graphs, i.e. events from which no work comes out (with the exception of the final event);
2) there should be no events (except outgoing) in the network charts, which are not preceded by at least one work;
3) when constructing network graphs, one should not allow two adjacent events to be connected by two or more jobs, which most often happens when depicting parallel jobs. This error leads to confusion due to the fact that two various works will have the same designation. To avoid this, it is recommended to introduce additional events and associate it with a subsequent dependency or dummy work;
4) there should be no closed loops in the network, i.e. chains connecting some events with themselves;
5) in addition, if any complex work can be started before the complete completion of the work immediately preceding them, then the latter is depicted as a series of sequentially performed works, each of which ends with a certain event.
6) if the execution of one of the activities requires obtaining the results of all the activities included in the event preceding it, and for another activity it is enough to obtain the result of only one or several of these activities, then a new event must be additionally introduced, as well as a fictitious activity linking new event from the old one.
The schedule constructed in compliance with these rules is a network model of project execution. In this case, at first, private network schedules are usually drawn up, covering work on separate parts of the general set of work that have independent significance, and then, by “stitching”, a complex (consolidated) schedule is obtained that covers the entire set of work to be performed.
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One of the firms decided to implement a computer information system. The appointed project manager compiled a list of actions (works) to be performed for this, and indicated the sequence of their implementation and the duration given in the table. Build a network diagram.
Note:
a) there must be one initiating and one terminating event in the network;
b) looking closely at the list of works, you will find that works A, B and C do not have
previous jobs (they only have subsequent jobs), which means they can be performed
in parallel, starting from the initial event;
c) avoid crossing paths;
d) direct work from left to right;
e) there should be as few fictitious jobs on the chart as possible.
| Work | Duration of work t, days | Subsequent work |
| A | 4 | D, E |
| D | 3 | O, N |
| O | 6 | End |
| E | 2 | K |
| K | 8 | P |
| N | 1 | P |
| P | 9 | End |
| B | 6 | F, G, H |
| F | 7 | K |
| G | 4 | L, M |
| L | 2 | End |
| C | 5 | I |
| H | 7 | I |
| I | 3 | M |
| M | 1 | End |
Video instruction
Scale network diagram
Calculate parameters network graphics measures to improve the management system. The network model is given tabularly (Table). The duration of the work is given in the form of minimum and maximum estimates. Required:- Calculate by tabular method all the main characteristics of work and events, find the critical path and its duration.
- Build a scaled network diagram.
- Estimate the probability of completing the entire complex of works in 30 days.
- Estimate the maximum possible time for the completion of the entire complex of works with a probability of 95%.
| Job code (i,j) | Duration |
|
tmin(i,j) | tmax(i,j) |
|
| 1,2 | 5 | 10 |
| 1,4 | 2 | 7 |
| 1,5 | 1 | 6 |
| 2,3 | 2 | 4,5 |
| 2,8 | 9 | 19 |
| 3,4 | 1 | 3,5 |
| 3,6 | 9 | 19 |
| 4,7 | 4 | 6,5 |
| 5,7 | 2 | 7 |
| 6,8 | 7 | 12 |
| 7,8 | 5 | 7,5 |
Decision we find using the service Network model. In our assignment, the duration of the work is given by two estimates - the minimum and maximum. The minimum estimate characterizes the duration of the work under the most favorable circumstances, and the maximum t max (i, j) - under the most unfavorable conditions. The duration of work in this case is considered as a random variable, which, as a result of implementation, can take any value in a given interval. Such estimates are called probabilistic (random), and their expected value t exp (i, j) is estimated by the formula
t exp (i,j)=(3 t min (i,j)+2 t max (i,j))/5
To characterize the degree of spread of possible values around the expected level, the dispersion index is used:
S 2 (i, j)=0.04(t max (i, j)-t min (i, j)) 2
Calculate the expected value and the variance.
t cool (1,2)=(3*5+2*10)/5=7
t cool (1,4)=(3*2+2*7)/5=4
t cool (1.5)=(3*1+2*6)/5=3
t cool (2.3)=(3*2+2*4.5)/5=3
t cool (2.8)=(3*9+2*19)/5=13
t cool (3.4)=(3*1+2*3.5)/5=2
t cool (3,6)=(3*9+2*19)/5=13
t cool (4.7)=(3*4+2*6.5)/5=5
t cool (5,7)=(3*2+2*7)/5=4
t cool (6.8)=(3*7+2*12)/5=9
t cool (7.8)=(3*5+2*7.5)/5=6
S 2 (1.2) \u003d 0.04 * (10-5) 2 \u003d 1
S 2 (1.4) \u003d 0.04 * (7-2) 2 \u003d 1
S 2 (1.5) \u003d 0.04 * (6-1) 2 \u003d 1
S 2 (2.3) \u003d 0.04 * (4.5-1) 2 \u003d 0.25
S 2 (2.8) \u003d 0.04 * (19-9) 2 \u003d 4
S 2 (3.4) \u003d 0.04 * (3.5-1) 2 \u003d 6.25
S 2 (3.6) \u003d 0.04 * (19-9) 2 \u003d 4
S 2 (4.7) \u003d 0.04 * (6.5-4) 2 \u003d 0.25
S 2 (5.7) \u003d 0.04 * (7-2) 2 \u003d 1
S 2 (6.8) \u003d 0.04 * (12-7) 2 \u003d 1
S 2 (7.8) \u003d 0.04 * (7.5-5) 2 \u003d 0.25
The obtained data will be entered in the table.
Table - Network model.
| Work (i,j) | Duration | Expected duration t exp (i,j) | Dispersion S 2 (i,j) |
|
tmin(i,j) | tmax(i,j) |
|||
| 1,2 | 5 | 10 | 7 | 1 |
| 1,4 | 2 | 7 | 4 | 1 |
| 1,5 | 1 | 6 | 3 | 1 |
| 2,3 | 2 | 4,5 | 3 | 0,25 |
| 2,8 | 9 | 19 | 13 | 4 |
| 3,4 | 1 | 3,5 | 2 | 6,25 |
| 3,6 | 9 | 19 | 13 | 4 |
| 4,7 | 4 | 6,5 | 5 | 0,25 |
| 5,7 | 2 | 7 | 4 | 1 |
| 6,8 | 7 | 12 | 9 | 1 |
| 7,8 | 5 | 7,5 | 6 | 0,25 |
Using the obtained data, we can find the main characteristics of the network model using a tabular method, the critical path and its duration.
Table - Tabular method for calculating the network diagram.
| CRC | Job code (i,j) | Duration of work t(i, j) | Early dates | Late dates | Reserves of time | |||
| t pH (i, j) | t ro (i,j) | t mon (i, j) | t by (i,j) | R p | Rc | |||
| 1 | 2 | 3 | 4 | 5 | 6 | 7 | 8 | 9 |
| 0 | 1,2 | 7 | 0 | 7 | 0 | 7 | 0 | 0 |
| 0 | 1,4 | 4 | 0 | 4 | 17 | 21 | 17 | 8 |
| 0 | 1,5 | 3 | 0 | 3 | 19 | 22 | 19 | 0 |
| 1 | 2,3 | 3 | 7 | 10 | 7 | 10 | 0 | 0 |
| 1 | 2,8 | 13 | 7 | 20 | 19 | 32 | 12 | 12 |
| 1 | 3,4 | 2 | 10 | 12 | 19 | 21 | 9 | 0 |
| 1 | 3,6 | 13 | 10 | 23 | 10 | 23 | 0 | 0 |
| 2 | 4,7 | 5 | 12 | 17 | 21 | 26 | 9 | 0 |
| 1 | 5,7 | 4 | 3 | 7 | 22 | 26 | 19 | 10 |
| 1 | 6,8 | 9 | 23 | 32 | 23 | 32 | 0 | 0 |
| 2 | 7,8 | 6 | 17 | 23 | 26 | 32 | 9 | 9 |
Thus, the critical path jobs are (1,2),(2,3),(3,6),(6,8). The duration of the critical path T kr =32.
Figure - Scale graph of the network model
To estimate the probability of completing the entire complex of works in 30 days, we need the following formula: P(t cr Z is the standard deviation of a random variable, S cr is the standard deviation calculated as the square root of the variance of the duration of the critical path. Correspondence between Z and Ф (Z) presented in the table.
Table - Table of the standard normal distribution.
| Z | F(Z) | Z | F(Z) | Z | F(Z) |
| 0 | 0.0000 | 1.0 | 0.6827 | 2.0 | 0.9643 |
| 0.1 | 0.0797 | 1.1 | 0.7287 | 2.1 | 0.9722 |
| 0.2 | 0.1585 | 1.2 | 0.7699 | 2.2 | 0.9786 |
| 0.3 | 0.2358 | 1.3 | 0.8064 | 2.3 | 0.9836 |
| 0.4 | 0.3108 | 1.4 | 0.8385 | 2.4 | 0.9876 |
| 0.5 | 0.3829 | 1.5 | 0.8664 | 2.5 | 0.9907 |
| 0.6 | 0.4515 | 1.6 | 0.8904 | 2.6 | 0.9931 |
| 0.7 | 0.5161 | 1.7 | 0.9104 | 2.7 | 0.9949 |
| 0.8 | 0.5763 | 1.8 | 0.9281 | 2.8 | 0.9963 |
| 0.9 | 0.6319 | 1.9 | 0.9545 | 2.9 | 0.9973 |
Critical path variance:
S 2 (L cr) \u003d S 2 (1.2) + S 2 (2.3) + S 2 (3.6) + S 2 (6.8) \u003d 1 + 0.25 + 4 + 1 \u003d 6 .25
S(L cr)=2.5
p(t cr<30)=0,5+0,5Ф((30-32)/2,5)=0,5-0,5Ф(0,8) = 0,5-0,5*0,5763=0,5-0,28815=0,213
The probability that the entire complex of works will be completed in no more than 30 days is 21.3%.
To determine the maximum possible time for the completion of the entire complex of works with a reliability of 95%, we will use the following formula: T=T cr +Z*S cr
To solve the problem, we find the value of the argument Z, which corresponds to a given probability of 95% (the value of the column Ф(Z) 0.9545*100% in Table 5 corresponds to Z=1.9).
T=32+1.9*2.5=36.8
The maximum term for completing the entire complex of works at a given probability level of 95% is only 36.8 days.
The construction of a network schedule begins with the compilation of a list of operations (works) to be performed (see Table 1). The sequence of operations in the list is arbitrary. The numbering order of operations is carried out in accordance with the sequence of their entry in the list. The list of operations is carefully thought out and, depending on the specific conditions, is detailed to a certain extent. The operations included in the list are characterized by a certain duration, which is established on the basis of current standards or by analogy with previously performed operations. After compiling the list of operations, proceed to the procedure for building a network.
Example. It is necessary to build a network schedule for the implementation of a complex of operations for the reconstruction of the workshop. The list of operations is presented in Table. 1. The final network diagram of the complex of operations is shown in Fig.1.
Decision. Graph operations except for operations 2→3 and 5→6 , are valid. The numbers in brackets assigned to the arcs indicate the duration of the corresponding operations. Operations a1 and a2 do not rely on any operations, therefore, on the graph, we will depict them as arcs emerging from event (1), which means the beginning of the execution of a complex of operations. Operations a3, a5 and a6 rely on surgery a1, therefore, on the graph, these arcs directly follow the arc a1. Event (2) means the end of the operation a1 and the start of the operations represented by the arcs emerging from this event. Operation a4, relies on operations a1 and a2. Graphically, this condition is reflected by sequentially displaying operations 1→3 and 3→4 and introducing a fictitious operation 2→3 . Event (3) is incident to operations 1→3 and 2→3 , therefore, the moment of completion of the event (3) will be the moment by which all the operations included in this event will be completed and the operation reflected by the arc emerging from it can be started. Similarly, taking into account the execution technology, the rest of the operations are shown on the graph. The final event (9) means the moment of completion of the entire complex of operations for the reconstruction of the workshop. Operation codes (see Table 1) consist of the numbers of the initial and final events and are practically entered into the list after the schedule is drawn up.
Table 1 - List of operations for building a network diagram
|
Operation |
Operation code |
the name of the operation |
Relies on operations |
Duration, days |
|
Preparatory work | ||||
|
Dismantling of old equipment | ||||
|
Foundation preparation for new equipment | ||||
|
Preparing for the installation of new equipment | ||||
|
Electrical work | ||||
|
Installation of new equipment | ||||
|
Connecting equipment to the mains | ||||
|
Adjustment and technological testing of equipment | ||||
|
Finishing work | ||||
|
Acceptance of the shop into operation |
The events and arcs of the constructed network graph (see Fig. 7.5) are numbered according to ranks. In practice, in the original network diagram, the elements, as a rule, have an unordered numbering. Therefore, after plotting a graph, it is recommended to renumber its elements using the methods discussed in the previous paragraph.
The construction of network diagrams of transient complexes of operations, when due to lack of time it is not possible to perform optimization calculations, is carried out taking into account technological and resource limitations. The construction of graphs for non-transitory complexes of operations, when there is enough time for their study, is performed only taking into account technological limitations. This approach ensures the minimum duration of the complex of operations. After the graph is built, its time parameters are calculated and optimization is performed for resources or other indicators, for which formal optimization methods are used.
Picture 1
For different levels of management, schedules of varying degrees of detail are drawn up. So in fig. 7.6 shows an enlarged network schedule for the reconstruction of the workshop. For specific performers, private network schedules are compiled with a greater degree of detail.
Assignment for seminar No. 4
Exercise 1. Bring the technological scheme of production developed in the course project in the specialty, list the main technological operations with an indication of the time of their implementation, as a result of which to build a network diagram of the production process and calculate all its time parameters.
A network schedule is a table designed to draw up a project plan and monitor its implementation. For its professional construction, there are specialized applications, such as MS Project. But for small businesses, and even more so for personal business needs, it makes no sense to buy specialized software and spend a lot of time learning the intricacies of working in it. With the construction of a network graph, the spreadsheet Excel, which is installed by most users, quite successfully copes. Let's find out how to perform the above task in this program.
You can build a network graph in Excel using a Gantt chart. Having the necessary knowledge, it is possible to compile a table of any complexity, ranging from the duty schedule of the watchmen to complex multi-level projects. Let's take a look at the algorithm for performing this task by making a simple network graph.
Stage 1: building the table structure
First of all, you need to create a table structure. It will be the framework of the network diagram. Typical elements of a network diagram are columns that indicate the serial number of a specific task, its name, the person responsible for its implementation and deadlines. But besides these main elements, there may be additional ones in the form of notes, etc.
This completes the creation of the table blank.
Stage 2: creating the timeline
Now we need to create the main part of our network diagram - the timeline. It will be a set of columns, each of which corresponds to one period of the project. Most often, one period is equal to one day, but there are cases when the value of the period is calculated in weeks, months, quarters, and even years.
In our example, we use the option when one period is equal to one day. Let's make a time scale for 30 days.
- We pass to the right border of the blank of our table. Starting from this border, we select a range with 30 columns, and the number of rows will be equal to the number of lines in the blank that we created earlier.
- Then click on the icon "Border" in mode "All Borders".
- After the boundaries are outlined, let's add the dates to the time scale. Let's say we control a project with a validity period of June 1-30, 2017. In this case, the name of the time scale columns must be set in accordance with the specified time interval. Of course, manually entering all the dates is quite tedious, so we will use an auto-complete tool called "Progression".
Insert the date into the first object of the time jackal header "01.06.2017". Move to tab "Home" and click on the icon "Fill". An additional menu opens, where you need to select an item "Progression…".
- Window is activated "Progression". In a group "Location" value should be marked "By lines", since we will fill the header, represented as a string. In a group "Type" option must be checked "Dates". In the block "Units" put the switch near the position "Day". In area "Step" must be a numeric expression "one". In area "Limit value" indicate the date 30.06.2017 . Click on OK.
- The header array will be populated with consecutive dates ranging from June 1 to June 30, 2017. But for the network diagram, we have cells that are too wide, which negatively affects the compactness of the table, and, therefore, its clarity. Therefore, we will carry out a series of manipulations to optimize the table.
Highlight the head of the timeline. Click on the selected fragment. In the list, we stop at the item "Cell Format". - In the formatting window that opens, move to the section "Alignment". In area "Orientation" set value "90 degrees", or move the element with the cursor "Inscription" up. Click on the button OK.
- After that, the names of the columns in the form of dates changed their orientation from horizontal to vertical. But due to the fact that the cells did not change their size, the names became unreadable, since they do not fit vertically into the designated elements of the sheet. To change this state of affairs, again select the contents of the header. Click on the icon "Format" located in the block "Cells". In the list, we stop at the option "AutoFit Row Height".
- After the described action, the names of the columns in height fit into the boundaries of the cells, but the width of the cells did not become more compact. Select the range of the timeline header again and click on the button "Format". This time, select the option from the list. "AutoFit Column Width".
- Now the table has become compact, and the grid elements have taken on a square shape.
Stage 3: Filling in the data
Stage 4: Conditional Formatting
At the next stage of working with the network diagram, we have to fill in with color those cells of the grid that correspond to the interval of the period for the implementation of a particular event. You can do this with conditional formatting.
- We mark the entire array of empty cells on the timeline, which is presented as a grid of square-shaped elements.
- Click on the icon "Conditional Formatting". It is located in the block "Styles" This will open a list. It should select the option "Create a Rule".
- A window is launched in which you want to create a rule. In the area for selecting the type of rule, we mark the item that implies the use of a formula to designate formatted elements. In field "Format Values" we need to set the selection rule, represented as a formula. For our particular case, it will look like this:
AND(G$1>=$D2;G$1<=($D2+$E2-1))
But in order for you to be able to convert this formula for your network graph, which quite possibly will have other coordinates, we should decipher the written formula.
"AND" is a built-in Excel function that checks if all values entered as its arguments are true. The syntax is:
AND(boolean1;boolean2;…)
In total, up to 255 booleans are used as arguments, but we only need two.
The first argument is written as an expression "G$1>=$D2". It checks that the value in the timeline is greater than or equal to the corresponding start date value for a particular event. Accordingly, the first link in given expression refers to the first cell of a row in the timeline, and the second cell refers to the first element of the event's start date column. dollar sign ( $ ) is set specifically so that the coordinates of the formula, which have this symbol, do not change, but remain absolute. And for your case, you must place the dollar signs in the appropriate places.
The second argument is represented by the expression "G$1<=($D2+$E2-1)» . It checks that the indicator on the timeline ( G$1) was less than or equal to the project completion date ( $D2+$E2-1). The timeline figure is calculated as in the previous expression, and the project end date is calculated by adding the project start date ( $D2) and its duration in days ( $E2). In order for the first day of the project to be included in the number of days, one is subtracted from this amount. The dollar sign plays the same role as in the previous expression.
If both arguments of the presented formula are true, then conditional formatting will be applied to the cells in the form of filling them with color.
To select a specific fill color, click on the button "Format…".
- In a new window, move to the section "Pouring". In a group "Background Colors" Various color options are available. We mark the color with which we want the cells of the days corresponding to the period of the specific task to be highlighted. For example, let's choose green. After the hue is reflected in the field "Sample", click on OK.
- After returning to the rule creation window, also click on the button OK.
- After the last activity, the network grid arrays corresponding to the period of the specific activity were colored green.
On this, the creation of a network diagram can be considered completed.
In the course of work, we created a network diagram. This is not the only version of such a table that can be created in Excel, but the basic principles for performing this task remain unchanged. Therefore, if desired, each user can improve the table presented in the example to suit their specific needs.
The construction of a network graph consists in the correct connection of the work-arrows with the help of events-circles. In this case, the correct connection of the arrows is as follows.
- each work in the network diagram must come out of an event, which means the end of all works, the result of which is necessary for its start.
- an event that marks the beginning of a particular work should not include the results of work, the completion of which is not required for the start of this work.
The graph is built from left to right, and each event with a higher serial number should be located to the right of the previous one. Arrows depicting works should be located from left to right.
The construction of the schedule begins with the image of work that does not require the results of other work to begin with. Such work can be called initial, since all other works of the complex will be performed only after they are fully completed. Depending on the specifics of the planned complex, there may be several initial works, or there may be only one. When placing the source work, it must be taken into account that on the network diagram, there should be only one source event.
On the fig.2 examples of building the beginning of a network graph are presented: fig.2(A) - for the variant with one original work (work a), fig.2(B) - for the variant with three original works (a, b, c).
Rice. 2. An example of building the beginning of a network diagram
In the process of further construction of the network diagram, it is necessary to adhere to the following rules.
If work "G" should be done only after the work is done "a", then on the graph it is depicted as a sequential chain of activities and events ( rice. 3).
Rice. 3. Image of sequentially performed works
If in order to perform work G" and " e” the result of the same work is needed, for example “c”, then the graph should look like this ( rice. 4).
Rice. 4. Image of works performed after the same work
If to perform one or more work (for example - " e”), the result of two or more works is required (for example, “ in" and " G”), then the graph will look like this ( rice. 5).
Rice. 5. Picture of work being done after several jobs
If to perform one or more jobs (for example "G" and "e" ) the result of only some part of another work is needed (for example, « a" ), then this work is divided into parts in such a way that its first part (for example, "a1" ) was executed until the result needed to start the first job ( "G" ), and the second and subsequent parts ( "a2", "a3" etc. - the rest of the work "a" ), were performed in parallel with the second work ( "e" ) and subsequent ( rice. 6).
Rice. 6. Image of work performed after partial completion of work
Two adjacent events can only be combined by one job. To depict parallel jobs, an intermediate event and a fictitious job ( rice. 7).
Rice. 7. Image of works having one start and end event
If the execution of any work (for example, "e") is possible only after obtaining the cumulative result of two or more parallel work (for example, "c" and "d"), and the execution of another work (for example, "e") - after receive the result of only one of them (for example, "in"), then in the network diagram it is necessary to introduce an additional event and fictitious work ( rice. eight).
Rice. 8. Using dummy work
The network should not be "dead ends" , i.e. intermediate events from which no work comes out (for example, event number 7 on rice. nine). It also shouldn't be "tails" , i.e. intermediate events that are not preceded by at least one work (for example, event No. 2 rice. nine).
Rice. 9. "Tails" and "dead ends" on the network diagram
8. The network should not contain closed loops consisting of interrelated jobs that create a closed circuit (for example, a chain of jobs "d", "G" on the rice. 10 (A)). This situation most likely indicates an error in compiling the list of works and determining their relationships. In this case, it is necessary to analyze the initial data and, depending on the conclusions drawn from the analysis, either redirect the work that creates the cycle to another event (if the work starting in this event requires its result, or if it is part of the overall result), or completely exclude it from the complex (if it is revealed that its result is not required). On the rice. 10 (B) presented the situation when the work "G" is part of the overall result.
Rice. 10(A). An example of a loop in a network diagram
Rice. 10(B). Eliminate a cycle in a network diagram
Each work in the network diagram must be uniquely defined, only by its inherent pair of events - there should not be events with the same numbers. For the correct numbering of events, proceed as follows: the numbering of events begins with the initial event, which is given the number 0. From the initial event (0), all outgoing works are deleted, on the remaining network, an event is again found that does not include any work. This event is given the number 1. Then the jobs emerging from the event 1 are crossed out, and the event that does not include any job is again found on the rest of the network, it is assigned the number 2, and so on until the final event. An example of network diagram numbering is shown in rice. eleven.
Rice. 11. Network diagram numbering order
There should be no fictitious jobs on the chart that duplicate information from other jobs. For example, a work that connects events #5 and 6 on rice. 12 (A) duplicates work Well”, the work connecting events No. 2 and 4 duplicates the work connecting events No. 2 and 3.
Rice. 12. Misuse of fictitious works
The shape of the graph should be simple, without unnecessary intersections. Most of the work should be depicted with horizontal lines. Most often, graphs are built from the initial event to the final one.
First, the network schedule is built in a draft version, while the main thing is not the appearance of the network, but the logical sequence of work. Then a graphical ordering of the network is carried out to reduce the number of mutually intersecting jobs.
The method of constructing network graphs described above has a number of disadvantages:
- Before plotting, it is quite difficult to identify errors in the original data.
- There are no clear criteria for the formulation of events, and the need to introduce fictitious works is not always obvious.
- Before building a network diagram, it is impossible to determine how many events and fictitious jobs will be in it. This makes it impossible to determine the size of the graph at the initial stages.
- At the initial drawing of the arrows, it is difficult to determine where it is better to direct them and how long they should be.
- The processes of wording and numbering events are largely subjective.
- The formalization of the procedures described above presents certain difficulties, which greatly complicates the development of adequate algorithms for plotting graphs using a computer.
- When planning complexes with a large number of works, building network diagrams in manual mode is almost impossible.
We propose a more systematic approach to the construction of network graphs, which largely eliminates these shortcomings. The proposed methodology consists of 4 stages.
