No. It would piss people off. This is an enclosed mall with a separate parking garage. You should protest at the historic park a quarter to half a mile away. P.s. protesters should always pick up after themselves.
You would have to check with the city ordinances, as well as the convention center/Providence Mall staff. At most places, you would need a permit if you take up space on someone else's property. You would have to clean up after your own mess and provide your own security.
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