Fever, fatigue, and dry hack are the most well-known symptoms of COVID-19 infection. Torment and throbs, nasal blockage, migraine, conjunctivitis, sore throat, the runs, loss of taste or smell, a rash, or discoloration of the fingers or toes are some of the less common adverse effects that a few people may experience. These manifestations are typically mellow and begin gradually. Only a few people are able to be contained without mild symptoms. Symptoms may vary from one country to another and change from common to mild or strong symptoms and may become a fleeting symptom. With the occurrence of mutations in Covid-19, new symptoms appear and differ from one country to another in their severity, and other symptoms disappear. But there are symptoms such as fever, fatigue and dehydration that persist despite these mutations.
4.1. Algorithm of the side effects of COVID-19 infection
Step 1: Assume that is the universe of discourse, R is the set of condition attributes and C is decision attribute.
Step 2: Find Pawlak’s and the boundary of any set .
Step 3: Remove any attribute , take as a base for topology and find the set .
Step 4: Calculate , and the boundary of the set .
Step 5: If the boundary of in Step 2 and Step 4 are the same, then is superfluous attribute.
Step 6: Repeat Step 3, Step 4 and Step 5 for all condition attributes and find reduct(R).
Step 1: Let be the set of patients, be the condition attributes, be the condition attributes and be the set of patients having + results. Then .
Step 2: pawlak’s and of is: , , .
Step 3: Case (i) Remove the attribute , then is a base for topology and we can deduce the set .
Step 4: The , and boundary of are: , and .
Step 5: Since , then is superfluous attribute which means it is not necessary for patients having + results.
Step 6:Case (ii) Remove the attribute , then . Therefore, , and .
Case (iii) Remove the attribute ,then . Hence, , and .
Case (iv) Remove the attribute ,then . Hence, , and .
Case (v) Remove the attribute , then . Hence, , and .
Therefore reduct(. Similarly, if is the set of patients having - result, then again reduct(.
Theorem 1. From the previous application, we conclude that only the symptoms that make up the reduct confirm the presence of the disease, therefore appropriate preventive measures must be taken, given a + situation