Elementary Comparison
Quick Summary
Elementary Comparison (EC) is similar to a Decision Table (DT) with binary values (Truth Table).
Use to:
Check the effect of each individual condition
Get a compact alternative to a Truth Table.
AND / OR operators
Condition combinations may be combined using logical AND or OR.
Example 1: A rule is true if ONE of the conditions is true. This implies OR. (
0/1are easier to distinguish visually and are therefore used instead ofY/N)| 0 0 | | 0 |
| 0 1 | → | 1 |
| 1 0 | | 1 |
| 0 1 | | 1 | Example 2: A rule is true only if ALL conditions are true. This implies AND. Notice two things:
The tables grows exponentially just like a DT: 23= 8 (2 values to the power of 3 conditions)
Only ONE compound condition results in the rule being true (last one:
| 1 1 1 |= | 1 |)| 0 0 0 | | 0 | | 0 0 1 | | 0 | | 0 1 0 | | 0 | | 0 1 1 | → | 0 | | 1 0 0 | | 0 | | 1 0 1 | | 0 | | 1 1 0 | | 0 | | 1 1 1 | | 1 |
Example 2 above illustrates that as long as ONE condition is false, the result remains the same. So instead of exhaustive testing (all 8 combinations), we may reduce the number to 4 rules:
| 1 1 1 |- the only scenario with a positive outcome| 0 1 1 |,| 1 0 1 |,| 1 1 0 |- where ANY ONE false condition negates the outcome. These tests check the effect of each individual condition.
The above allows for reducing the testing effort as part of a calculated risk. There is still a risk that the software logic was written in such a way that e.g. | 0 0 1 | causes a bug.
Full DT vs. ET
✅ Full Decision Table (All 8 Combinations)
This covers all possible combinations of 3 binary conditions (2³ = 8 rules).
1
Y
Y
Y
Approve
2
Y
Y
N 🔴
Reject
3
Y
N 🔴
Y
Reject
4
Y
N
N
Reject
5
N🔴
Y
Y
Reject
6
N
Y
N
Reject
7
N
N
Y
Reject
8
N
N
N
Reject
✂️ Reduced ET Table (Just 4 Rules)
We pick Rule 1, which leads to the Approve decision, and Rules with 🔴 - where a single N condition negates the outcome.
1
Y
Y
Y
Approve
2
Y
Y
N🔴
Reject
3
Y
N🔴
Y
Reject
4
N🔴
Y
Y
Reject
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