In wikipedia article one can read that:
In current theory, post-1972, various interpretations (i.e. theories) of quantum mechanics violate different aspects of Local Realism. But some interpretations only violate aspects of a related principle, known as counterfactual definiteness. [bolded by myself]
Could you please help me understand the subject by explaining to me concept of counterfactual definiteness? It is stated that
In quantum mechanics, counterfactual definiteness (CFD) is the ability to speak meaningfully of the definiteness of the results of measurements that have not been performed (i.e. the ability to assume the existence of objects, and properties of objects, even when they have not been measured).
How can there exist values for each measurement (realism) but one cannot "speak meaningfully of definiteness of the results (...)" (violation of counterfactual definiteness)?
Let us use example of throwing a coin (not real world coin, but coin violating or not violating realism, locality, counterfactual definiteness and such as we please).
With local realism I can (with enough information and computation) state with certainity that result will be for example tails. Is that correct?
With realism (without local realism) I can only say (knowing the forces I used throwing the coin etc.) that there is let's say 75% chance of getting tails and 25% of getting heads. The outcome doesn't deppend on fact of my observation and that alone is realism. Is that correct?
How does counterfactual definiteness apply to that?
Please - explain to me these three concepts (realism, local realism, counterfactual definiteness) and relations between them).