In which cases A-score get reduce

AFAIK each and every score that adds up to our total A-score has an expiry date. First the certifications as you mentioned, when a certification expires corresponding A-score is reduced. Similarly A-score acquired due to posts or comments also get expired after a certain period of time. So if you were active in Community in January and you were credited an increment in A-score, the incremented value will be decremented again after some time of inactivity.

Thanks Harsha.

1. Are you saying that every A-score has a validity which we get from post or comments?

OR

2. A-score are only get reduce when I do not active long time in community, You just said "after some time"  in your reply... is there any specific days or months? because my A score get reduced today and I was active in last week/month.

I don't know the specific time after which a score expires infact I don't think there is a specific time. AFAIK A-scores are updated manually by a person from Appian. All the activities of a user is monitored (I think I heard somewhere once every week/fortnight)- no. of answers provided, correct answers, posts everything and accordingly they provide score for the same. Thus A-score keeps on incrementing/decrementing based on user activites. What exact criteria they follow to provide the scores I am not aware of but I know the accuracy/quality of your posts and answers are kept in consideration as well. Hope it clarifies a bit more.

Yes.. Thanks.