The arena is real; the wavefunction is its visible coordinate. Real enough to be readable off the world, too thin to be the world.
"Is the wavefunction real?" runs two questions together. Does something in the world correspond to it? And is it the complete story of what exists? CSD's answers come apart cleanly: yes, and emphatically no.
Yes: the quantum state is not a fiction or a mere gambling position. Every arena point projects to a definite state, so the state tracks a genuine feature of the world -- you could read it off the world's actual configuration if you had access.
No: the state is radically incomplete. The projection that produces it is many-to-one, and everything that decides measurement outcomes -- the fibre coordinate, the basin the trajectory occupies -- lives in what the projection forgets. Treating the state as the whole world is exactly the move that generates the measurement problem; treating it as a lossy coordinate dissolves it.
The state's dual character is structural, not rhetorical. Functionally it is epistemic: it summarises what a preparation pins down, and its update on measurement is learning. Ontologically its supports are disjoint -- distinct states describe disjoint sets of arena points -- which is why the reality theorems aimed at overlapping-support models do not bite.
The programme's discipline is to refuse the shorter slogans in both directions: "the wavefunction is everything" overclaims what the sector carries -- the fibre analysis places record-forming content above it at higher dimension, on a constraint chain that stops short of proving the base cannot carry it -- and "the wavefunction is nothing" ignores that it is a faithful coordinate of the real arena.
The formal content is the projection structure: a measurable many-to-one pi from the arena to the projective sector, the epistemic measure exact on the base and spread on the fibre, and the record layer's theorems placing outcome-deciding structure in the fibre at N >= 3. The operational stratum's state notion -- density operators and effects -- is proved consistent with the volume stratum wherever both speak.
Source links are pinned to a commit, so they do not drift. The anchors above are checked mechanically against the Lean tree on every build. The mathematics is not, and cannot be: that is a human responsibility and it rests with the author.
Part of Constraint-Surface Dynamics · Formalised in csd-lean4.
Google Analytics counts visits to this page, which stores cookies in your browser. They record how the page was reached, not who you are, and nothing is passed on. Blocking cookies for this site breaks nothing here. Details.