In wikipedia source: http://en.wikipedia.org/wiki/Quadratic_residue(adsbygoogle = window.adsbygoogle || []).push({});

under "composite modulus" section

I found the line

"On the other hand, if we want to know if there is a solution for x less than some given limit c, this problem is NP-complete;however, this is a fixed-parameter tractable problem, where c is the parameter."

what does it mean by "given limit c , and fixed parameter tractable with c as parameter". Does this mean regardless of large values are given for c as a limit , we can solve the quadratic congruence without knowing the factorization? or does it has any other meaning?

what is the limit of c such that we cannot solve quadratic congruence using fpt

If i am wrong or obscure in my question, please notify me.

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# Fpt problem in quadratic residues

Can you offer guidance or do you also need help?

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