i want to know weather the community user can able to view the knowledge article published .
without enabling the knowledge user check box in the user details.
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Simple answer is
If you intend to use your community as a public knowledge base for unauthenticated (or guest) users, you can do so without purchasing communities licenses. For example, guest users can access publicly available community pages to read content, review knowledge articles, and perform tasks which do not require them to log in (such as creating cases).
Knowledge user checkbox is for internal users.
By default all internal users can read articles. However some licenses like the Knowledge Only User licenses, require the “AllowViewKnowledge” permission on the user’s profile. To give a user the “AllowViewKnowledge” permission on their profile, activate the permission on a cloned profile and assign the cloned profile to the user.
According to this, users can view articles without that check box. The checkbox you are referring to gives agents the ability to do more than just read articles (Quote from link):
To do more than read articles, agents need the Knowledge User license.
You just misunderstood "knowledge user" checkbox!
This checkbox means user has permission to write/draft/publish articles - means having this checkbox - you are author.
Other user means reader don't need it. They can just read the article if they have object level Read access + Article is available to them based on their channel(Customer, Partner, Public).