David Sacks

Arithmetical Sacks Forcing

We answer a question of Jockusch by constructing a hyperimmunefree minimal degree below a 1-generic one. To do this we introduce a new forcing notion called arithmetical Sacks forcing. Some other applications are presented.

Libman-Sacks Endocarditis

In 1924 Libman and Sacks published an account of atypical, sterile, verrucous vegetations on the heart in systemic lupus erythematosus (SLE). [1] Clusters of verrucae, looking like mulberries, were described on the ventricular surface of the posterior leaflet of the mitral valve and found at postmortem. The leaflet and the chordae tendinae are often adherent to the endocardium of the ventricula...

Projective Absoluteness under Sacks Forcing

We show that Σ3-absoluteness under Sacks forcing is equivalent to the Sacks measurability of every ∆2 set of reals. We also show that Sacks forcing is the weakest forcing notion among all of the preorders which always add a new real with respect to Σ3 forcing absoluteness.

Pulmonary anthrax caused by contaminated sacks.

A Sacks real out of nowhere

There is a proper countable support iteration of length ω adding no new reals at finite stages and adding a Sacks real in the limit.