wrong answer from solve?
var('t')
test3 = -4*cos(t)^4 + 4*cos(t)^2 - 1
sage: solve(test3==0,t)
[]
When actually the equation is equivalent to (cos(t))^2 = 1/2 and it does have solutions.
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So then, if solve returns [], that does not mean "there are no solutions". It means, "I didn't find any solutions". Similarly, if it does return a list of solutions, I guess that means "Here are the solutions I found", rather than, "Here are all the solutions." If this is the case, the documentation should say so up front. It says, "if there are no solutions it returns an empty list" but says nothing about the converse.
