
2.7 inferenCe engine 37
An example can be given as follows:
Rule: IF the teacher is present in the class
THEN students must be present in the class
Given fact: The teacher is present and teaching in the class on the given
day
Conclusion: Students must be present in the class
2.7.2 Modus Tollens
Modus tollens is given as:
When B is known to be false and a rule states “If A, then B,” then A is false.
An example can be given as follows:
Rule: IF the teacher is present in the class
THEN students must be present in the class
Given fact: Students were absent on the given day
Conclusion: The teacher must be absent, which is a new fact
In simple ...