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Trevor Wilson
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It is consistent that the nonstationary ideal on $\omega_1$ is strong but not pre-saturated. Baumgartner and Taylor proved in the aforementioned paper that strong ideals are preserved by c.c.c. forcing and asked whether the same is true for pre-saturated ideals. The answer to this question is negative, implying a negative answer to the question I posted above. Apparently this was first proved by Veličković in the paper Forcing axioms and stationary sets (which I cannot seem to access online) from ZFC + SPFA. Another example of a c.c.c. forcing that destroys pre-saturation may be found in a more recent paper by Larson and Yorioka, Another c.c.c. forcing that destroys presaturation, assuming the consistency of ZF + AD.

I don't know if a negative answer can be forced from only a Woodin cardinal (which is provable in ZFCequiconsistent with the existence of a presaturated ideal and also with the existence of a strong ideal.)

It is consistent that the nonstationary ideal on $\omega_1$ is strong but not pre-saturated. Baumgartner and Taylor proved in the aforementioned paper that strong ideals are preserved by c.c.c. forcing and asked whether the same is true for pre-saturated ideals. The answer to this question is negative, implying a negative answer to the question I posted above. Apparently this was first proved by Veličković in the paper Forcing axioms and stationary sets (which I cannot seem to access online) from ZFC + SPFA. Another example of a c.c.c. forcing that destroys pre-saturation may be found in a more recent paper by Larson and Yorioka, Another c.c.c. forcing that destroys presaturation, assuming the consistency of ZF + AD.

I don't know if a negative answer is provable in ZFC.

It is consistent that the nonstationary ideal on $\omega_1$ is strong but not pre-saturated. Baumgartner and Taylor proved in the aforementioned paper that strong ideals are preserved by c.c.c. forcing and asked whether the same is true for pre-saturated ideals. The answer to this question is negative, implying a negative answer to the question I posted above. Apparently this was first proved by Veličković in the paper Forcing axioms and stationary sets (which I cannot seem to access online) from ZFC + SPFA. Another example of a c.c.c. forcing that destroys pre-saturation may be found in a more recent paper by Larson and Yorioka, Another c.c.c. forcing that destroys presaturation, assuming the consistency of ZF + AD.

I don't know if a negative answer can be forced from only a Woodin cardinal (which is equiconsistent with the existence of a presaturated ideal and also with the existence of a strong ideal.)

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Trevor Wilson
  • 5.5k
  • 29
  • 46

It is consistent that the nonstationary ideal on $\omega_1$ is strong but not pre-saturated. Baumgartner and Taylor proved in the aforementioned paper that strong ideals are preserved by c.c.c. forcing and asked whether the same is true for pre-saturated ideals. The answer to this question is negative, implying a negative answer to the question I posted above. Apparently this was first proved by Veličković in the paper Forcing axioms and stationary sets (which I cannot seem to access online) from ZFC + SPFA. Another example of a c.c.c. forcing that destroys pre-saturation may be found in a more recent paper by Larson and Yorioka, Another c.c.c. forcing that destroys presaturation, assuming the consistency of ZF + AD.

I don't know if a negative answer is provable in ZFC.