Answer:
Yes
Explanation:
Closed-form means that the poem must fit every criteria of the poem, and that it cannot veer off the format. If it was an open-form, you can veer off the format, but in this case, you must change it to fit into the criteria given to you.
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It's called Iambic Pentameter -- it's a rhyme scheme found in Shakespearean sonnets that must be composed of 10 syllables.
Closed form is simply superset of types of poetry such as haikus, tonkas, and well, sonnets.
So, it's not against the laws of closed form poetry per se, it's just against the laws of Shakespearean sonnets.