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LeanPool.NavierStokesAndEuler.Euler.PacketInductionStage

The packet stage invariant #

GrowthData contains the Euler state, activation time and strain decomposition used to prove gradient growth. Stage adds the source bounds and frame guards needed to construct the next packet. Separating them lets the growth theorem apply without assuming the successor construction's hypotheses. All cumulative bounds use only earlier indices.

The transverse packet data of a parent in the fixed reference plane: its frame, inverse frame and strain along the centre trajectory, against which a stage's ParentFrame is measured.

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    The state, activation and strain bounds used by the growth argument. The common horizon and Sobolev realisation also support comparison with other Euler evolutions. These data impose no hypotheses on a successor packet.

    • The parent: the volume-preserving particle map, with its velocity and acceleration, that carries the current Euler state on [0, parent.T]. Its frame, strain and curvature are the coefficients every estimate reads.

    • The current Euler solution on the parent: a pointwise classical Evolution, its Sobolev realisation regularity (converted to an ordinary evolution by the contradiction), its label bounds, and its odd symmetry, which makes the strain at the origin equal to the velocity gradient there (strain_origin).

    • time :

      The activation time of the most recently added packet (0 at the base stage). The divergent quantity activationGradient is the velocity gradient at (time, 0).

    • time_nonneg : 0 self.time

      The activation time is a time of the stage solution.

    • horizon_eq : self.parent.T = self.time + 2 * EulerPacketSourceScaleSequence.timeWidth S.J S.X n

      The stage solution lives exactly 2·timeWidth n beyond the activation. This gives time < parent.T, so the activation is an interior time, and it lets the next stage's horizon nest strictly inside this one.

    • Every stage horizon lies inside the base horizon, so all stage solutions can be compared with one hypothetical evolution on [0, baseHorizon].

    • The frame of the parent strain along the centre trajectory at the activation time: background B, ray m, velocity v, shear coefficient, and the bounds G on B and error on the remainder.

    • The leading rank-one part of the strain at the centre has shear previousShear n, the target shear of the latest packet. This is the term the growth argument isolates.

    • The background B is bounded one shear level lower, by frameConstant·(1 + olderShear n), so that the leading term dominates it.

    • The remainder after B and the rank-one shear are removed is at most priorError n, an inverse fourth root of the previous frequency, which is negligible against the leading shear.

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      A full packet stage, including the induction hypotheses needed by the successor construction. Stage.toGrowthData retains only the state, activation and frame bounds needed for gradient growth. The full record keeps its original projection interface.

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        The positive post-activation time width puts activation inside the horizon.

        The common base horizon bounds every activation time by one.

        Forget the source bounds and frame guards that only the successor construction needs.

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          The activation time is strictly inside the stage horizon.

          Every activation occurs before time one.

          theorem EulerPacketInduction.Stage.time_pos {c B : } {S : EulerPacketInductionScales.Scales c B} {n : } (P : Stage S n) (hn : n 0) :
          0 < P.time