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François G. Dorais
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Let $\mathbb{P}$ and $\mathbb{Q}$ be two forcing notions. Recall that we say $\mathbb{Q}$ is a subforcing of $\mathbb{P}$ if there exists a regular embedding $\mathbb{Q} \to \text{r.o.}(\mathbb{P}).$

Question. Let $\mathbb{P} \in \{Add(\omega, \kappa), Col(\omega_1, \kappa) \}.$

(1) Is there a subforcing of $\mathbb{P}$ which is not Proper?

(2) Is there a subforcing of $\mathbb{P}$ which is not semi-Proper?

Remark. In "Subalgebras of Cohen algebras need not be Cohen" it is shownSubalgebras of Cohen algebras need not be Cohen, Koppelberg and Shelah show that there is a subalgebra of Cohen forcing which is not Cohen.

Let $\mathbb{P}$ and $\mathbb{Q}$ be two forcing notions. Recall that we say $\mathbb{Q}$ is a subforcing of $\mathbb{P}$ if there exists a regular embedding $\mathbb{Q} \to \text{r.o.}(\mathbb{P}).$

Question. Let $\mathbb{P} \in \{Add(\omega, \kappa), Col(\omega_1, \kappa) \}.$

(1) Is there a subforcing of $\mathbb{P}$ which is not Proper?

(2) Is there a subforcing of $\mathbb{P}$ which is not semi-Proper?

Remark. In "Subalgebras of Cohen algebras need not be Cohen" it is shown that there is a subalgebra of Cohen forcing which is not Cohen.

Let $\mathbb{P}$ and $\mathbb{Q}$ be two forcing notions. Recall that we say $\mathbb{Q}$ is a subforcing of $\mathbb{P}$ if there exists a regular embedding $\mathbb{Q} \to \text{r.o.}(\mathbb{P}).$

Question. Let $\mathbb{P} \in \{Add(\omega, \kappa), Col(\omega_1, \kappa) \}.$

(1) Is there a subforcing of $\mathbb{P}$ which is not Proper?

(2) Is there a subforcing of $\mathbb{P}$ which is not semi-Proper?

Remark. In Subalgebras of Cohen algebras need not be Cohen, Koppelberg and Shelah show that there is a subalgebra of Cohen forcing which is not Cohen.

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Mohammad Golshani
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Bad subforcings of nice forcing notions

Let $\mathbb{P}$ and $\mathbb{Q}$ be two forcing notions. Recall that we say $\mathbb{Q}$ is a subforcing of $\mathbb{P}$ if there exists a regular embedding $\mathbb{Q} \to \text{r.o.}(\mathbb{P}).$

Question. Let $\mathbb{P} \in \{Add(\omega, \kappa), Col(\omega_1, \kappa) \}.$

(1) Is there a subforcing of $\mathbb{P}$ which is not Proper?

(2) Is there a subforcing of $\mathbb{P}$ which is not semi-Proper?

Remark. In "Subalgebras of Cohen algebras need not be Cohen" it is shown that there is a subalgebra of Cohen forcing which is not Cohen.