For real variables p , s , a , b , c p,s,a,b,c p , s , a , b , c , set
K = a 2 + b 2 + c 2 − 2 ( a b + b c + c a ) , S = p 2 + s 2 , C = S + K . K=a^2+b^2+c^2-2(ab+bc+ca),\qquad S=p^2+s^2,\qquad C=S+K. K = a 2 + b 2 + c 2 − 2 ( ab + b c + c a ) , S = p 2 + s 2 , C = S + K .
The shear components and wall rates are
P = K p − 2 a 2 + b 2 + c 2 + a b − 2 b c + a c , P=Kp-2a^2+b^2+c^2+ab-2bc+ac, P = K p − 2 a 2 + b 2 + c 2 + ab − 2 b c + a c ,
Q = K s + 3 ( − b 2 + c 2 + a b − a c ) , Q=Ks+\sqrt{3}(-b^2+c^2+ab-ac), Q = K s + 3 ( − b 2 + c 2 + ab − a c ) ,
r 1 = − S + 2 p , r 2 = − S − p + 3 s , r 3 = − S − p − 3 s . r_1=-S+2p,\qquad r_2=-S-p+\sqrt{3}s,\qquad r_3=-S-p-\sqrt{3}s. r 1 = − S + 2 p , r 2 = − S − p + 3 s , r 3 = − S − p − 3 s .
These functions define the normalized vacuum Bianchi IX vector field
( P , Q , r 1 a , r 2 b , r 3 c ) (P,Q,r_1a,r_2b,r_3c) ( P , Q , r 1 a , r 2 b , r 3 c ) .
For y = ( m , u , v , w ) ∈ R 4 y=(m,u,v,w)\in\mathbb R^4 y = ( m , u , v , w ) ∈ R 4 , define
K ( u , v , w ) = u 2 + v 2 + w 2 − 2 ( u v + v w + w u ) , κ = u ( v + w − u ) , K(u,v,w)=u^2+v^2+w^2-2(uv+vw+wu),\qquad \kappa=u(v+w-u), K ( u , v , w ) = u 2 + v 2 + w 2 − 2 ( uv + v w + w u ) , κ = u ( v + w − u ) ,
F m = − v 2 + w 2 + u ( v − w ) − m κ , F u = 1 2 ( 1 − m 2 − ( v − w ) 2 + u 2 ) u , F_m=-v^2+w^2+u(v-w)-m\kappa,\qquad
F_u=\tfrac12(1-m^2-(v-w)^2+u^2)u, F m = − v 2 + w 2 + u ( v − w ) − mκ , F u = 2 1 ( 1 − m 2 − ( v − w ) 2 + u 2 ) u ,
F v = ( m − 1 − κ ) v , F w = ( − m − 1 − κ ) w , F = ( F m , F u , F v , F w ) , F_v=(m-1-\kappa)v,\qquad F_w=(-m-1-\kappa)w,\qquad
F=(F_m,F_u,F_v,F_w), F v = ( m − 1 − κ ) v , F w = ( − m − 1 − κ ) w , F = ( F m , F u , F v , F w ) ,
and E ( m , v ) = ( m − 1 ) 2 + v 2 E(m,v)=(m-1)^2+v^2 E ( m , v ) = ( m − 1 ) 2 + v 2 .
For x = ( p , s , a , b , c ) x=(p,s,a,b,c) x = ( p , s , a , b , c ) , put
ψ ( p , z ) = 3 z 1 + p , Π ( x ) = ( ψ ( p , s ) , ψ ( p , a ) , ψ ( p , b ) , ψ ( p , c ) ) . \psi(p,z)=\frac{\sqrt3\,z}{1+p},\qquad
\Pi(x)=(\psi(p,s),\psi(p,a),\psi(p,b),\psi(p,c)). ψ ( p , z ) = 1 + p 3 z , Π ( x ) = ( ψ ( p , s ) , ψ ( p , a ) , ψ ( p , b ) , ψ ( p , c )) .
For y = ( m , u , v , w ) y=(m,u,v,w) y = ( m , u , v , w ) , set D ( y ) = 3 + m 2 + K ( u , v , w ) D(y)=3+m^2+K(u,v,w) D ( y ) = 3 + m 2 + K ( u , v , w ) and
Ξ A ( y ) = ( A − 1 , A m 3 , A u 3 , A v 3 , A w 3 ) , Ξ ( y ) = Ξ 6 / D ( y ) ( y ) . \Xi_A(y)=\left(A-1,\frac{Am}{\sqrt3},\frac{Au}{\sqrt3},
\frac{Av}{\sqrt3},\frac{Aw}{\sqrt3}\right),\qquad
\Xi(y)=\Xi_{6/D(y)}(y). Ξ A ( y ) = ( A − 1 , 3 A m , 3 A u , 3 A v , 3 A w ) , Ξ ( y ) = Ξ 6/ D ( y ) ( y ) .
Write N ( x ) = ( P , Q , r 1 a , r 2 b , r 3 c ) N(x)=(P,Q,r_1a,r_2b,r_3c) N ( x ) = ( P , Q , r 1 a , r 2 b , r 3 c ) for the normalized vector field
and C ( x ) = C ( p , s , a , b , c ) \mathcal C(x)=C(p,s,a,b,c) C ( x ) = C ( p , s , a , b , c ) for its constraint.
The normalized and projective state spaces are R 5 \mathbb R^5 R 5 and R 4 \mathbb R^4 R 4
with their finite-product norms. The maps Π , Ξ , D , F \Pi,\Xi,D,F Π , Ξ , D , F act on these state spaces.
Define the core radius, angle, and clock factor by
r ( m , v ) = ( m − 1 ) 2 + v 2 , θ ( m , v ) = arsinh 1 − m v , d ( r , u , w ) = 1 − ( u − w ) 2 r 2 . r(m,v)=\sqrt{(m-1)^2+v^2},\qquad
\theta(m,v)=\operatorname{arsinh}\frac{1-m}{v},\qquad
d(r,u,w)=1-\frac{(u-w)^2}{r^2}. r ( m , v ) = ( m − 1 ) 2 + v 2 , θ ( m , v ) = arsinh v 1 − m , d ( r , u , w ) = 1 − r 2 ( u − w ) 2 .
For y = ( m , u , v , w ) y=(m,u,v,w) y = ( m , u , v , w ) , write r y = r ( m , v ) r_y=r(m,v) r y = r ( m , v ) , θ y = θ ( m , v ) \theta_y=\theta(m,v) θ y = θ ( m , v ) ,
and d y = d ( r y , u , w ) d_y=d(r_y,u,w) d y = d ( r y , u , w ) . All quotients use the total convention x / 0 = 0 x/0=0 x /0 = 0 .
The core state space is R 3 \mathbb R^3 R 3 with coordinates Y = ( r , u , p ) Y=(r,u,p) Y = ( r , u , p ) .
Define
η ( m , u , v , w ) = ( r ( m , v ) , u , v w ) , ι z ( r , u , p ) = ( 1 − r tanh z , u , r cosh z , p r / cosh z ) . \eta(m,u,v,w)=(r(m,v),u,vw),\qquad
\iota_z(r,u,p)=\left(1-r\tanh z,u,\frac r{\cosh z},
\frac p{r/\cosh z}\right). η ( m , u , v , w ) = ( r ( m , v ) , u , v w ) , ι z ( r , u , p ) = ( 1 − r tanh z , u , cosh z r , r / cosh z p ) .
For fixed ( z , Y ) (z,Y) ( z , Y ) put v = r / cosh z v=r/\cosh z v = r / cosh z , w = p / v w=p/v w = p / v , d = d ( r , u , w ) d=d(r,u,w) d = d ( r , u , w ) , and define
V ( z , Y ) = ( − κ ( u , v , w ) − tanh z ( u − w ) 2 / r d , u [ − r / 2 + tanh z + w / cosh z + ( u 2 − w 2 ) / ( 2 r ) ] d , − 2 p ( 1 + κ ( u , v , w ) ) r d ) . \mathcal V(z,Y)=\left(
\frac{-\kappa(u,v,w)-\tanh z\,(u-w)^2/r}{d},\quad
\frac{u[-r/2+\tanh z+w/\cosh z+(u^2-w^2)/(2r)]}{d},\quad
\frac{-2p(1+\kappa(u,v,w))}{rd}\right). V ( z , Y ) = ( d − κ ( u , v , w ) − tanh z ( u − w ) 2 / r , d u [ − r /2 + tanh z + w / cosh z + ( u 2 − w 2 ) / ( 2 r )] , r d − 2 p ( 1 + κ ( u , v , w )) ) .
For real k k k , put ε k = 1 / ( 10000 k ) \varepsilon_k=1/(10000k) ε k = 1/ ( 10000 k ) and define
K k = { ( m , u , v , w ) : ∣ E ( m , v ) − k 2 ∣ ≤ 1 / 8 , v ≥ 1 , 0 ≤ u ≤ ε k , 0 ≤ v w ≤ ε k } . \mathcal K_k=\{(m,u,v,w): |E(m,v)-k^2|\leq1/8,\quad v\geq1,
\quad0\leq u\leq\varepsilon_k,\quad0\leq vw\leq\varepsilon_k\}. K k = {( m , u , v , w ) : ∣ E ( m , v ) − k 2 ∣ ≤ 1/8 , v ≥ 1 , 0 ≤ u ≤ ε k , 0 ≤ v w ≤ ε k } .
Write X = R 5 X=\mathbb R^5 X = R 5 , Y = R 4 Y=\mathbb R^4 Y = R 4 , and let α x , t 0 \alpha_{x,t_0} α x , t 0 be the
maximal solution of α ′ = N ( α ) \alpha'=N(\alpha) α ′ = N ( α ) with initial value x x x at t 0 t_0 t 0
and domain I max ( x , t 0 ) I_{\max}(x,t_0) I m a x ( x , t 0 ) . Put
J x , t 0 ( t ) = d x α x , t 0 ( t ) , Ψ t 0 ( y , t ) = Π ( α Ξ ( y ) , t 0 ( t ) ) , J_{x,t_0}(t)=d_x\alpha_{x,t_0}(t),\qquad
\Psi_{t_0}(y,t)=\Pi(\alpha_{\Xi(y),t_0}(t)), J x , t 0 ( t ) = d x α x , t 0 ( t ) , Ψ t 0 ( y , t ) = Π ( α Ξ ( y ) , t 0 ( t )) ,
J y , t 0 ( t ) = d Π α Ξ ( y ) , t 0 ( t ) ∘ J Ξ ( y ) , t 0 ( t ) ∘ d Ξ y . \mathcal J_{y,t_0}(t)=d\Pi_{\alpha_{\Xi(y),t_0}(t)}
\circ J_{\Xi(y),t_0}(t)\circ d\Xi_y. J y , t 0 ( t ) = d Π α Ξ ( y ) , t 0 ( t ) ∘ J Ξ ( y ) , t 0 ( t ) ∘ d Ξ y .
Write G ( y ) = 6 F ( y ) / D ( y ) G(y)=6F(y)/D(y) G ( y ) = 6 F ( y ) / D ( y ) , λ ( y ) = 6 r y d y / D ( y ) \lambda(y)=6r_yd_y/D(y) λ ( y ) = 6 r y d y / D ( y ) , and
S k ( R , U , P ) = ( R , k U , P ) S_k(R,U,P)=(R,kU,P) S k ( R , U , P ) = ( R , k U , P ) . Define
P y ξ = d η y ξ − d θ y ξ V ( θ y , η ( y ) ) , W y , t 0 , w ( t ) = P Ψ t 0 ( y , t ) ( J y , t 0 ( t ) w ) . \mathcal P_y\xi=d\eta_y\xi-d\theta_y\xi\,\mathcal V(\theta_y,\eta(y)),
\qquad \mathcal W_{y,t_0,w}(t)=
\mathcal P_{\Psi_{t_0}(y,t)}(\mathcal J_{y,t_0}(t)w). P y ξ = d η y ξ − d θ y ξ V ( θ y , η ( y )) , W y , t 0 , w ( t ) = P Ψ t 0 ( y , t ) ( J y , t 0 ( t ) w ) .
The entrance parametrization and radial exit factor are
e ( k , u , w ) = ( 1 + k 2 − 1 , u , 1 , w ) , e(k,u,w)=(1+\sqrt{k^2-1},u,1,w), e ( k , u , w ) = ( 1 + k 2 − 1 , u , 1 , w ) ,
f y = V ( θ y , η ( y ) ) 0 , c y = − tanh θ y , h y = c y + f y / r y , ρ y = c y / h y . f_y=\mathcal V(\theta_y,\eta(y))_0,\qquad c_y=-\tanh\theta_y,
\qquad h_y=c_y+f_y/r_y,\qquad \rho_y=c_y/h_y. f y = V ( θ y , η ( y ) ) 0 , c y = − tanh θ y , h y = c y + f y / r y , ρ y = c y / h y .
For projective initial data y y y , put
A y , t 0 ( t ) = 1 + ( α Ξ ( y ) , t 0 ( t ) ) 0 . A_{y,t_0}(t)=1+(\alpha_{\Xi(y),t_0}(t))_0. A y , t 0 ( t ) = 1 + ( α Ξ ( y ) , t 0 ( t ) ) 0 .
Coordinates of three-vectors are indexed by 0 , 1 , 2 0,1,2 0 , 1 , 2 ; projective
coordinates are indexed by m , u , v , w m,u,v,w m , u , v , w .
For Y ∈ R 3 Y\in\mathbb R^3 Y ∈ R 3 , put x Y = Ξ ( e ( Y ) ) x_Y=\Xi(e(Y)) x Y = Ξ ( e ( Y )) ,
β Y ( t ) = Ψ 0 ( e ( Y ) , t ) \beta_Y(t)=\Psi_0(e(Y),t) β Y ( t ) = Ψ 0 ( e ( Y ) , t ) , and
H Y = { t > 0 : t ∈ I max ( x Y , 0 ) , ( β Y ( t ) ) v = 1 } , T ( Y ) = inf H Y , F ( Y ) = η ( β Y ( T ( Y ) ) ) . H_Y=\{t>0:t\in I_{\max}(x_Y,0),\ (\beta_Y(t))_v=1\},
\qquad T(Y)=\inf H_Y,\qquad F(Y)=\eta(\beta_Y(T(Y))). H Y = { t > 0 : t ∈ I m a x ( x Y , 0 ) , ( β Y ( t ) ) v = 1 } , T ( Y ) = inf H Y , F ( Y ) = η ( β Y ( T ( Y ))) .
The infimum uses the total real-order convention. Write Valid ( Y ) \operatorname{Valid}(Y) Valid ( Y )
when T ( Y ) T(Y) T ( Y ) is the least element of H Y H_Y H Y , every t ∈ [ 0 , T ( Y ) ] t\in[0,T(Y)] t ∈ [ 0 , T ( Y )] lies in
I max ( x Y , 0 ) I_{\max}(x_Y,0) I m a x ( x Y , 0 ) with A e ( Y ) , 0 ( t ) > 0 A_{e(Y),0}(t)>0 A e ( Y ) , 0 ( t ) > 0 , the active wall is strictly
above one for 0 < t < T ( Y ) 0<t<T(Y) 0 < t < T ( Y ) , and
d g α x Y , 0 ( T ( Y ) ) N ( α x Y , 0 ( T ( Y ) ) ) < 0 , g ( x ) = ( Π ( x ) ) v . dg_{\alpha_{x_Y,0}(T(Y))}N(\alpha_{x_Y,0}(T(Y)))<0,
\qquad g(x)=(\Pi(x))_v. d g α x Y , 0 ( T ( Y )) N ( α x Y , 0 ( T ( Y ))) < 0 , g ( x ) = ( Π ( x ) ) v .
All vector and operator norms below use the finite-product supremum norm.
For real variables p , s , a , b , c p,s,a,b,c p , s , a , b , c , set
K = a 2 + b 2 + c 2 − 2 ( a b + b c + c a ) , S = p 2 + s 2 , C = S + K . K=a^2+b^2+c^2-2(ab+bc+ca),\qquad S=p^2+s^2,\qquad C=S+K. K = a 2 + b 2 + c 2 − 2 ( ab + b c + c a ) , S = p 2 + s 2 , C = S + K .
The shear components and wall rates are
P = K p − 2 a 2 + b 2 + c 2 + a b − 2 b c + a c , P=Kp-2a^2+b^2+c^2+ab-2bc+ac, P = K p − 2 a 2 + b 2 + c 2 + ab − 2 b c + a c ,
Q = K s + 3 ( − b 2 + c 2 + a b − a c ) , Q=Ks+\sqrt{3}(-b^2+c^2+ab-ac), Q = K s + 3 ( − b 2 + c 2 + ab − a c ) ,
r 1 = − S + 2 p , r 2 = − S − p + 3 s , r 3 = − S − p − 3 s . r_1=-S+2p,\qquad r_2=-S-p+\sqrt{3}s,\qquad r_3=-S-p-\sqrt{3}s. r 1 = − S + 2 p , r 2 = − S − p + 3 s , r 3 = − S − p − 3 s .
These functions define the normalized vacuum Bianchi IX vector field
( P , Q , r 1 a , r 2 b , r 3 c ) (P,Q,r_1a,r_2b,r_3c) ( P , Q , r 1 a , r 2 b , r 3 c ) .
For y = ( m , u , v , w ) ∈ R 4 y=(m,u,v,w)\in\mathbb R^4 y = ( m , u , v , w ) ∈ R 4 , define
K ( u , v , w ) = u 2 + v 2 + w 2 − 2 ( u v + v w + w u ) , κ = u ( v + w − u ) , K(u,v,w)=u^2+v^2+w^2-2(uv+vw+wu),\qquad \kappa=u(v+w-u), K ( u , v , w ) = u 2 + v 2 + w 2 − 2 ( uv + v w + w u ) , κ = u ( v + w − u ) ,
F m = − v 2 + w 2 + u ( v − w ) − m κ , F u = 1 2 ( 1 − m 2 − ( v − w ) 2 + u 2 ) u , F_m=-v^2+w^2+u(v-w)-m\kappa,\qquad
F_u=\tfrac12(1-m^2-(v-w)^2+u^2)u, F m = − v 2 + w 2 + u ( v − w ) − mκ , F u = 2 1 ( 1 − m 2 − ( v − w ) 2 + u 2 ) u ,
F v = ( m − 1 − κ ) v , F w = ( − m − 1 − κ ) w , F = ( F m , F u , F v , F w ) , F_v=(m-1-\kappa)v,\qquad F_w=(-m-1-\kappa)w,\qquad
F=(F_m,F_u,F_v,F_w), F v = ( m − 1 − κ ) v , F w = ( − m − 1 − κ ) w , F = ( F m , F u , F v , F w ) ,
and E ( m , v ) = ( m − 1 ) 2 + v 2 E(m,v)=(m-1)^2+v^2 E ( m , v ) = ( m − 1 ) 2 + v 2 .
For x = ( p , s , a , b , c ) x=(p,s,a,b,c) x = ( p , s , a , b , c ) , put
ψ ( p , z ) = 3 z 1 + p , Π ( x ) = ( ψ ( p , s ) , ψ ( p , a ) , ψ ( p , b ) , ψ ( p , c ) ) . \psi(p,z)=\frac{\sqrt3\,z}{1+p},\qquad
\Pi(x)=(\psi(p,s),\psi(p,a),\psi(p,b),\psi(p,c)). ψ ( p , z ) = 1 + p 3 z , Π ( x ) = ( ψ ( p , s ) , ψ ( p , a ) , ψ ( p , b ) , ψ ( p , c )) .
For y = ( m , u , v , w ) y=(m,u,v,w) y = ( m , u , v , w ) , set D ( y ) = 3 + m 2 + K ( u , v , w ) D(y)=3+m^2+K(u,v,w) D ( y ) = 3 + m 2 + K ( u , v , w ) and
Ξ A ( y ) = ( A − 1 , A m 3 , A u 3 , A v 3 , A w 3 ) , Ξ ( y ) = Ξ 6 / D ( y ) ( y ) . \Xi_A(y)=\left(A-1,\frac{Am}{\sqrt3},\frac{Au}{\sqrt3},
\frac{Av}{\sqrt3},\frac{Aw}{\sqrt3}\right),\qquad
\Xi(y)=\Xi_{6/D(y)}(y). Ξ A ( y ) = ( A − 1 , 3 A m , 3 A u , 3 A v , 3 A w ) , Ξ ( y ) = Ξ 6/ D ( y ) ( y ) .
Write N ( x ) = ( P , Q , r 1 a , r 2 b , r 3 c ) N(x)=(P,Q,r_1a,r_2b,r_3c) N ( x ) = ( P , Q , r 1 a , r 2 b , r 3 c ) for the normalized vector field
and C ( x ) = C ( p , s , a , b , c ) \mathcal C(x)=C(p,s,a,b,c) C ( x ) = C ( p , s , a , b , c ) for its constraint.
The normalized and projective state spaces are R 5 \mathbb R^5 R 5 and R 4 \mathbb R^4 R 4
with their finite-product norms. The maps Π , Ξ , D , F \Pi,\Xi,D,F Π , Ξ , D , F act on these state spaces.
The projective vector field in normalized time is
G ( y ) = 6 D ( y ) F ( y ) . G(y)=\frac6{D(y)}F(y). G ( y ) = D ( y ) 6 F ( y ) .
Write X = R 5 X=\mathbb R^5 X = R 5 , Y = R 4 Y=\mathbb R^4 Y = R 4 , and let α x , t 0 \alpha_{x,t_0} α x , t 0 be the
maximal solution of α ′ = N ( α ) \alpha'=N(\alpha) α ′ = N ( α ) with initial value x x x at t 0 t_0 t 0
and domain I max ( x , t 0 ) I_{\max}(x,t_0) I m a x ( x , t 0 ) . Put
J x , t 0 ( t ) = d x α x , t 0 ( t ) , Ψ t 0 ( y , t ) = Π ( α Ξ ( y ) , t 0 ( t ) ) , J_{x,t_0}(t)=d_x\alpha_{x,t_0}(t),\qquad
\Psi_{t_0}(y,t)=\Pi(\alpha_{\Xi(y),t_0}(t)), J x , t 0 ( t ) = d x α x , t 0 ( t ) , Ψ t 0 ( y , t ) = Π ( α Ξ ( y ) , t 0 ( t )) ,
J y , t 0 ( t ) = d Π α Ξ ( y ) , t 0 ( t ) ∘ J Ξ ( y ) , t 0 ( t ) ∘ d Ξ y . \mathcal J_{y,t_0}(t)=d\Pi_{\alpha_{\Xi(y),t_0}(t)}
\circ J_{\Xi(y),t_0}(t)\circ d\Xi_y. J y , t 0 ( t ) = d Π α Ξ ( y ) , t 0 ( t ) ∘ J Ξ ( y ) , t 0 ( t ) ∘ d Ξ y .
Put c = u ( v + w − u ) c=u(v+w-u) c = u ( v + w − u ) , s ( m , u , v , w ) = m − 1 − c s(m,u,v,w)=m-1-c s ( m , u , v , w ) = m − 1 − c ,
b ( m , u , v , w ) = ( 1 − m 2 − ( v − w ) 2 + u 2 ) / 2 b(m,u,v,w)=(1-m^2-(v-w)^2+u^2)/2 b ( m , u , v , w ) = ( 1 − m 2 − ( v − w ) 2 + u 2 ) /2 ,
D ( m , u , v , w ) = 3 + m 2 + K ( u , v , w ) D(m,u,v,w)=3+m^2+K(u,v,w) D ( m , u , v , w ) = 3 + m 2 + K ( u , v , w ) , and r ( m , v ) = ( m − 1 ) 2 + v 2 r(m,v)=\sqrt{(m-1)^2+v^2} r ( m , v ) = ( m − 1 ) 2 + v 2 .
Define
C μ = { ( m , u , v , w ) : ∣ − m − μ ∣ ≤ 1 / 2 , 0 ≤ u ≤ 1 / 10000 , 0 ≤ v , w ≤ 1 } , \mathcal C_\mu=\{(m,u,v,w):|-m-\mu|\leq1/2,
\ 0\leq u\leq1/10000,\ 0\leq v,w\leq1\}, C μ = {( m , u , v , w ) : ∣ − m − μ ∣ ≤ 1/2 , 0 ≤ u ≤ 1/10000 , 0 ≤ v , w ≤ 1 } ,
ω − ( y ) = s ( − y m , y u , y v , y w ) , H ( y ) = F ( y ) / ω − ( y ) . \omega_-(y)=s(-y_m,y_u,y_v,y_w),\qquad H(y)=F(y)/\omega_-(y). ω − ( y ) = s ( − y m , y u , y v , y w ) , H ( y ) = F ( y ) / ω − ( y ) .
For a normalized trajectory write
β ( t ) = Π ( α x , t 0 ( t ) ) , A ( t ) = 1 + ( α x , t 0 ( t ) ) 0 , I = I max ( x , t 0 ) . \beta(t)=\Pi(\alpha_{x,t_0}(t)),\quad A(t)=1+(\alpha_{x,t_0}(t))_0,
\quad I=I_{\max}(x,t_0). β ( t ) = Π ( α x , t 0 ( t )) , A ( t ) = 1 + ( α x , t 0 ( t ) ) 0 , I = I m a x ( x , t 0 ) .
For p = ( μ , u , w ) ∈ R 3 p=(\mu,u,w)\in\mathbb R^3 p = ( μ , u , w ) ∈ R 3 , set e ( p ) = ( − μ , u , 1 , w ) e(p)=(-\mu,u,1,w) e ( p ) = ( − μ , u , 1 , w ) ,
x p = Ξ ( e ( p ) ) x_p=\Xi(e(p)) x p = Ξ ( e ( p )) , and
T − ( p ) = inf { t > 0 : t ∈ I max ( x p , 0 ) , ( Ψ 0 ( e ( p ) , t ) ) w = 1 } , P − ( p ) = Ψ 0 ( e ( p ) , T − ( p ) ) . T_-(p)=\inf\{t>0:t\in I_{\max}(x_p,0),\ (\Psi_0(e(p),t))_w=1\},
\qquad P_-(p)=\Psi_0(e(p),T_-(p)). T − ( p ) = inf { t > 0 : t ∈ I m a x ( x p , 0 ) , ( Ψ 0 ( e ( p ) , t ) ) w = 1 } , P − ( p ) = Ψ 0 ( e ( p ) , T − ( p )) .
Let V − ( p ) V_-(p) V − ( p ) mean that this infimum is a least element, the full interval
[ 0 , T − ( p ) ] [0,T_-(p)] [ 0 , T − ( p )] lies in the maximal domain with positive A A A , the growing wall
is below one before the endpoint, and its normalized-time derivative is
strictly positive at the endpoint. The infimum has its total real-order meaning.
Write e + ( R , u , w ) = ( 1 + R 2 − 1 , u , 1 , w ) e_+(R,u,w)=(1+\sqrt{R^2-1},u,1,w) e + ( R , u , w ) = ( 1 + R 2 − 1 , u , 1 , w ) ,
e − ( R , u , w ) = ( 1 − R 2 − 1 , u , 1 , w ) e_-(R,u,w)=(1-\sqrt{R^2-1},u,1,w) e − ( R , u , w ) = ( 1 − R 2 − 1 , u , 1 , w ) ,
p − ( R , u , w ) = ( R 2 − 1 − 1 , u , w ) p_-(R,u,w)=(\sqrt{R^2-1}-1,u,w) p − ( R , u , w ) = ( R 2 − 1 − 1 , u , w ) , and
R ( m , u , v , w ) = ( − m , u , w , v ) \mathcal R(m,u,v,w)=(-m,u,w,v) R ( m , u , v , w ) = ( − m , u , w , v ) .
The physical connection coordinates are
C ( p ) = ( ( − P − ( p ) 0 − 1 ) 2 + 1 , P − ( p ) 1 , P − ( p ) 2 ) . \mathscr C(p)=\left(\sqrt{(-P_-(p)_0-1)^2+1},P_-(p)_1,P_-(p)_2\right). C ( p ) = ( ( − P − ( p ) 0 − 1 ) 2 + 1 , P − ( p ) 1 , P − ( p ) 2 ) .
Below T T T denotes the canonical core return time from e + e_+ e + and
F ( Y ) = η ( Ψ 0 ( e + ( Y ) , T ( Y ) ) ) F(Y)=\eta(\Psi_0(e_+(Y),T(Y))) F ( Y ) = η ( Ψ 0 ( e + ( Y ) , T ( Y ))) its radial and wall coordinates.
Let R ( Y ) = C ( p − ( Y ) ) \mathscr R(Y)=\mathscr C(p_-(Y)) R ( Y ) = C ( p − ( Y )) , t r ( Y ) = T − ( p − ( Y ) ) t_r(Y)=T_-(p_-(Y)) t r ( Y ) = T − ( p − ( Y )) ,
G = R ∘ F G=\mathscr R\circ F G = R ∘ F , and t G ( Y ) = T ( Y ) + t r ( F ( Y ) ) t_G(Y)=T(Y)+t_r(F(Y)) t G ( Y ) = T ( Y ) + t r ( F ( Y )) .
A cone direction at Y Y Y has d 0 = 1 d_0=1 d 0 = 1 ,
∣ d 1 ∣ ≤ Y 1 |d_1|\leq\sqrt{Y_1} ∣ d 1 ∣ ≤ Y 1 , ∣ d 2 ∣ ≤ Y 2 |d_2|\leq\sqrt{Y_2} ∣ d 2 ∣ ≤ Y 2 .
For a map H H H with positive output walls, its positive cone property means
d H ( Y ) d dH(Y)d d H ( Y ) d has positive radial component and
∣ ( d H ( Y ) d ) i ∣ ≤ H ( Y ) i ( d H ( Y ) d ) 0 |(dH(Y)d)_i|\leq\sqrt{H(Y)_i}(dH(Y)d)_0 ∣ ( d H ( Y ) d ) i ∣ ≤ H ( Y ) i ( d H ( Y ) d ) 0 for i = 1 , 2 i=1,2 i = 1 , 2 .
For real variables p , s , a , b , c p,s,a,b,c p , s , a , b , c , set
K = a 2 + b 2 + c 2 − 2 ( a b + b c + c a ) , S = p 2 + s 2 , C = S + K . K=a^2+b^2+c^2-2(ab+bc+ca),\qquad S=p^2+s^2,\qquad C=S+K. K = a 2 + b 2 + c 2 − 2 ( ab + b c + c a ) , S = p 2 + s 2 , C = S + K .
The shear components and wall rates are
P = K p − 2 a 2 + b 2 + c 2 + a b − 2 b c + a c , P=Kp-2a^2+b^2+c^2+ab-2bc+ac, P = K p − 2 a 2 + b 2 + c 2 + ab − 2 b c + a c ,
Q = K s + 3 ( − b 2 + c 2 + a b − a c ) , Q=Ks+\sqrt{3}(-b^2+c^2+ab-ac), Q = K s + 3 ( − b 2 + c 2 + ab − a c ) ,
r 1 = − S + 2 p , r 2 = − S − p + 3 s , r 3 = − S − p − 3 s . r_1=-S+2p,\qquad r_2=-S-p+\sqrt{3}s,\qquad r_3=-S-p-\sqrt{3}s. r 1 = − S + 2 p , r 2 = − S − p + 3 s , r 3 = − S − p − 3 s .
These functions define the normalized vacuum Bianchi IX vector field
( P , Q , r 1 a , r 2 b , r 3 c ) (P,Q,r_1a,r_2b,r_3c) ( P , Q , r 1 a , r 2 b , r 3 c ) .
For y = ( m , u , v , w ) ∈ R 4 y=(m,u,v,w)\in\mathbb R^4 y = ( m , u , v , w ) ∈ R 4 , define
K ( u , v , w ) = u 2 + v 2 + w 2 − 2 ( u v + v w + w u ) , κ = u ( v + w − u ) , K(u,v,w)=u^2+v^2+w^2-2(uv+vw+wu),\qquad \kappa=u(v+w-u), K ( u , v , w ) = u 2 + v 2 + w 2 − 2 ( uv + v w + w u ) , κ = u ( v + w − u ) ,
F m = − v 2 + w 2 + u ( v − w ) − m κ , F u = 1 2 ( 1 − m 2 − ( v − w ) 2 + u 2 ) u , F_m=-v^2+w^2+u(v-w)-m\kappa,\qquad
F_u=\tfrac12(1-m^2-(v-w)^2+u^2)u, F m = − v 2 + w 2 + u ( v − w ) − mκ , F u = 2 1 ( 1 − m 2 − ( v − w ) 2 + u 2 ) u ,
F v = ( m − 1 − κ ) v , F w = ( − m − 1 − κ ) w , F = ( F m , F u , F v , F w ) , F_v=(m-1-\kappa)v,\qquad F_w=(-m-1-\kappa)w,\qquad
F=(F_m,F_u,F_v,F_w), F v = ( m − 1 − κ ) v , F w = ( − m − 1 − κ ) w , F = ( F m , F u , F v , F w ) ,
and E ( m , v ) = ( m − 1 ) 2 + v 2 E(m,v)=(m-1)^2+v^2 E ( m , v ) = ( m − 1 ) 2 + v 2 .
For x = ( p , s , a , b , c ) x=(p,s,a,b,c) x = ( p , s , a , b , c ) , put
ψ ( p , z ) = 3 z 1 + p , Π ( x ) = ( ψ ( p , s ) , ψ ( p , a ) , ψ ( p , b ) , ψ ( p , c ) ) . \psi(p,z)=\frac{\sqrt3\,z}{1+p},\qquad
\Pi(x)=(\psi(p,s),\psi(p,a),\psi(p,b),\psi(p,c)). ψ ( p , z ) = 1 + p 3 z , Π ( x ) = ( ψ ( p , s ) , ψ ( p , a ) , ψ ( p , b ) , ψ ( p , c )) .
For y = ( m , u , v , w ) y=(m,u,v,w) y = ( m , u , v , w ) , set D ( y ) = 3 + m 2 + K ( u , v , w ) D(y)=3+m^2+K(u,v,w) D ( y ) = 3 + m 2 + K ( u , v , w ) and
Ξ A ( y ) = ( A − 1 , A m 3 , A u 3 , A v 3 , A w 3 ) , Ξ ( y ) = Ξ 6 / D ( y ) ( y ) . \Xi_A(y)=\left(A-1,\frac{Am}{\sqrt3},\frac{Au}{\sqrt3},
\frac{Av}{\sqrt3},\frac{Aw}{\sqrt3}\right),\qquad
\Xi(y)=\Xi_{6/D(y)}(y). Ξ A ( y ) = ( A − 1 , 3 A m , 3 A u , 3 A v , 3 A w ) , Ξ ( y ) = Ξ 6/ D ( y ) ( y ) .
Write N ( x ) = ( P , Q , r 1 a , r 2 b , r 3 c ) N(x)=(P,Q,r_1a,r_2b,r_3c) N ( x ) = ( P , Q , r 1 a , r 2 b , r 3 c ) for the normalized vector field
and C ( x ) = C ( p , s , a , b , c ) \mathcal C(x)=C(p,s,a,b,c) C ( x ) = C ( p , s , a , b , c ) for its constraint.
The normalized and projective state spaces are R 5 \mathbb R^5 R 5 and R 4 \mathbb R^4 R 4
with their finite-product norms. The maps Π , Ξ , D , F \Pi,\Xi,D,F Π , Ξ , D , F act on these state spaces.
The projective vector field in normalized time is
G ( y ) = 6 D ( y ) F ( y ) . G(y)=\frac6{D(y)}F(y). G ( y ) = D ( y ) 6 F ( y ) .
Write X = R 5 X=\mathbb R^5 X = R 5 , Y = R 4 Y=\mathbb R^4 Y = R 4 , and let α x , t 0 \alpha_{x,t_0} α x , t 0 be the
maximal solution of α ′ = N ( α ) \alpha'=N(\alpha) α ′ = N ( α ) with initial value x x x at t 0 t_0 t 0
and domain I max ( x , t 0 ) I_{\max}(x,t_0) I m a x ( x , t 0 ) . Put
J x , t 0 ( t ) = d x α x , t 0 ( t ) , Ψ t 0 ( y , t ) = Π ( α Ξ ( y ) , t 0 ( t ) ) , J_{x,t_0}(t)=d_x\alpha_{x,t_0}(t),\qquad
\Psi_{t_0}(y,t)=\Pi(\alpha_{\Xi(y),t_0}(t)), J x , t 0 ( t ) = d x α x , t 0 ( t ) , Ψ t 0 ( y , t ) = Π ( α Ξ ( y ) , t 0 ( t )) ,
J y , t 0 ( t ) = d Π α Ξ ( y ) , t 0 ( t ) ∘ J Ξ ( y ) , t 0 ( t ) ∘ d Ξ y . \mathcal J_{y,t_0}(t)=d\Pi_{\alpha_{\Xi(y),t_0}(t)}
\circ J_{\Xi(y),t_0}(t)\circ d\Xi_y. J y , t 0 ( t ) = d Π α Ξ ( y ) , t 0 ( t ) ∘ J Ξ ( y ) , t 0 ( t ) ∘ d Ξ y .
For Y = ( k , u , w ) ∈ R 3 Y=(k,u,w)\in\mathbb R^3 Y = ( k , u , w ) ∈ R 3 , define
e − ( Y ) = ( 1 − k 2 − 1 , u , 1 , w ) , x Y = Ξ ( e − ( Y ) ) , β Y ( t ) = Ψ 0 ( e − ( Y ) , t ) , g ( x ) = ( Π ( x ) ) v . e_-(Y)=(1-\sqrt{k^2-1},u,1,w),\quad x_Y=\Xi(e_-(Y)),\quad
\beta_Y(t)=\Psi_0(e_-(Y),t),\quad g(x)=(\Pi(x))_v. e − ( Y ) = ( 1 − k 2 − 1 , u , 1 , w ) , x Y = Ξ ( e − ( Y )) , β Y ( t ) = Ψ 0 ( e − ( Y ) , t ) , g ( x ) = ( Π ( x ) ) v .
For any real height η \eta η , put
H η , Y = { t > 0 : t ∈ I max ( x Y , 0 ) , g ( α x Y , 0 ( t ) ) = η } , H_{\eta,Y}=\{t>0:t\in I_{\max}(x_Y,0),\ g(\alpha_{x_Y,0}(t))=\eta\}, H η , Y = { t > 0 : t ∈ I m a x ( x Y , 0 ) , g ( α x Y , 0 ( t )) = η } ,
T η ( Y ) = inf H η , Y , P η ( Y ) = β Y ( T η ( Y ) ) . T_\eta(Y)=\inf H_{\eta,Y},\qquad P_\eta(Y)=\beta_Y(T_\eta(Y)). T η ( Y ) = inf H η , Y , P η ( Y ) = β Y ( T η ( Y )) .
The infimum uses the total real-order convention. Let
TailValid η ( Y ) \operatorname{TailValid}_\eta(Y) TailValid η ( Y ) mean that T η ( Y ) T_\eta(Y) T η ( Y ) is the least
element of H η , Y H_{\eta,Y} H η , Y , and, writing T = T η ( Y ) T=T_\eta(Y) T = T η ( Y ) , that
t ∈ I max ( x Y , 0 ) , 1 + ( α x Y , 0 ( t ) ) 0 > 0 ( 0 ≤ t ≤ T ) , t\in I_{\max}(x_Y,0),\quad 1+(\alpha_{x_Y,0}(t))_0>0
\quad(0\leq t\leq T), t ∈ I m a x ( x Y , 0 ) , 1 + ( α x Y , 0 ( t ) ) 0 > 0 ( 0 ≤ t ≤ T ) ,
g ( α x Y , 0 ( t ) ) > η ( 0 ≤ t < T ) , g(\alpha_{x_Y,0}(t))>\eta\quad(0\leq t<T), g ( α x Y , 0 ( t )) > η ( 0 ≤ t < T ) ,
d g α x Y , 0 ( t ) N ( α x Y , 0 ( t ) ) < 0 , ∣ ( Π ( α x Y , 0 ( t ) ) ) w ∣ < 1 / 2 ( 0 ≤ t ≤ T ) . dg_{\alpha_{x_Y,0}(t)}N(\alpha_{x_Y,0}(t))<0,\quad
|(\Pi(\alpha_{x_Y,0}(t)))_w|<1/2\quad(0\leq t\leq T). d g α x Y , 0 ( t ) N ( α x Y , 0 ( t )) < 0 , ∣ ( Π ( α x Y , 0 ( t )) ) w ∣ < 1/2 ( 0 ≤ t ≤ T ) .
All vector and operator norms use the finite-product supremum norms.
For y ∈ R 4 y\in\mathbb R^4 y ∈ R 4 , put x y = Ξ ( y ) x_y=\Xi(y) x y = Ξ ( y ) ,
T + ( y ) = inf { t > 0 : t ∈ I max ( x y , 0 ) , ( Ψ 0 ( y , t ) ) v = 1 } , P + ( y ) = Ψ 0 ( y , T + ( y ) ) . T_+(y)=\inf\{t>0:t\in I_{\max}(x_y,0),\ (\Psi_0(y,t))_v=1\},
\qquad P_+(y)=\Psi_0(y,T_+(y)). T + ( y ) = inf { t > 0 : t ∈ I m a x ( x y , 0 ) , ( Ψ 0 ( y , t ) ) v = 1 } , P + ( y ) = Ψ 0 ( y , T + ( y )) .
Let V + ( y ) V_+(y) V + ( y ) mean that this infimum is a least element, the full interval
[ 0 , T + ( y ) ] [0,T_+(y)] [ 0 , T + ( y )] lies in the maximal domain with
1 + ( α x y , 0 ( t ) ) 0 > 0 1+(\alpha_{x_y,0}(t))_0>0 1 + ( α x y , 0 ( t ) ) 0 > 0 , the active wall
is below one before the endpoint, and its normalized-time derivative is
strictly positive throughout the interval. The infimum has its total
real-order meaning.
For y = ( m , u , v , w ) y=(m,u,v,w) y = ( m , u , v , w ) define the cyclic chart by
H ( y ) = ( m + 1 ) 2 + K ( u , v , w ) , A ( y ) = ( 1 − 4 ( m + 1 ) / H , 4 v / H , 4 w / H , 4 u / H ) . H(y)=(m+1)^2+K(u,v,w),\qquad
\mathcal A(y)=(1-4(m+1)/H,4v/H,4w/H,4u/H). H ( y ) = ( m + 1 ) 2 + K ( u , v , w ) , A ( y ) = ( 1 − 4 ( m + 1 ) / H , 4 v / H , 4 w / H , 4 u / H ) .
Its normalized symmetry is
A ( p , s , a , b , c ) = ( ( − p + 3 s ) / 2 , ( − 3 p − s ) / 2 , b , c , a ) . A(p,s,a,b,c)=((-p+\sqrt3s)/2,(-\sqrt3p-s)/2,b,c,a). A ( p , s , a , b , c ) = (( − p + 3 s ) /2 , ( − 3 p − s ) /2 , b , c , a ) .
Put z h ( Y ) = A ( P h ( Y ) ) z_h(Y)=\mathcal A(P_h(Y)) z h ( Y ) = A ( P h ( Y )) and
T ( h , Y ) = T h ( Y ) + T + ( z h ( Y ) ) , P ( h , Y ) = P + ( z h ( Y ) ) , x Y c = A Ξ ( e − ( Y ) ) . \mathcal T(h,Y)=T_h(Y)+T_+(z_h(Y)),\qquad
\mathcal P(h,Y)=P_+(z_h(Y)),\qquad x_Y^c=A\Xi(e_-(Y)). T ( h , Y ) = T h ( Y ) + T + ( z h ( Y )) , P ( h , Y ) = P + ( z h ( Y )) , x Y c = A Ξ ( e − ( Y )) .
Write r ( m , v ) = ( m − 1 ) 2 + v 2 r(m,v)=\sqrt{(m-1)^2+v^2} r ( m , v ) = ( m − 1 ) 2 + v 2 and g ∗ ( x ) = ( Π ( x ) ) v g_*(x)=(\Pi(x))_v g ∗ ( x ) = ( Π ( x ) ) v .
In the era formulas below, F F F denotes the core return map and
G = R ∘ F G=\mathscr R\circ F G = R ∘ F its composition with reflection.
For Z = ( R , u , w ) Z=(R,u,w) Z = ( R , u , w ) use the natural height h ∗ ( Z ) = η ( ( R − 2 ) / 2 ) J h_*(Z)=\eta((R-2)/2)^J h ∗ ( Z ) = η (( R − 2 ) /2 ) J and define
S ∗ ( Z ) = P ( h ∗ ( Z ) , Z ) S_*(Z)=\mathcal P(h_*(Z),Z) S ∗ ( Z ) = P ( h ∗ ( Z ) , Z ) ,
R ∗ ( Z ) = r ( S ∗ ( Z ) 0 , S ∗ ( Z ) 2 ) R_*(Z)=r(S_*(Z)_0,S_*(Z)_2) R ∗ ( Z ) = r ( S ∗ ( Z ) 0 , S ∗ ( Z ) 2 ) ,
Q ∗ ( Z ) = 2 / R ∗ ( Z ) Q_*(Z)=2/R_*(Z) Q ∗ ( Z ) = 2/ R ∗ ( Z ) and t ∗ ( Z ) = T ( h ∗ ( Z ) , Z ) t_*(Z)=\mathcal T(h_*(Z),Z) t ∗ ( Z ) = T ( h ∗ ( Z ) , Z ) .
The complete era maps are
Z m = F ∘ G m , S m = S ∗ ∘ Z m , R m = R ∗ ∘ Z m , P m = 2 / R m . Z_m=F\circ G^m,\qquad S_m=S_*\circ Z_m,\qquad
R_m=R_*\circ Z_m,\qquad P_m=2/R_m. Z m = F ∘ G m , S m = S ∗ ∘ Z m , R m = R ∗ ∘ Z m , P m = 2/ R m .
For a graph Γ = ( U , W ) \Gamma=(U,W) Γ = ( U , W ) write Γ [ r ] = ( r , U ( r ) , W ( r ) ) \Gamma[r]=(r,U(r),W(r)) Γ [ r ] = ( r , U ( r ) , W ( r )) ,
ϕ m ( r ) = P m ( Γ [ r ] ) \phi_m(r)=P_m(\Gamma[r]) ϕ m ( r ) = P m ( Γ [ r ]) , k m ( r ) = R m ( Γ [ r ] ) k_m(r)=R_m(\Gamma[r]) k m ( r ) = R m ( Γ [ r ]) ,
u m ( r ) = S m ( Γ [ r ] ) 1 u_m(r)=S_m(\Gamma[r])_1 u m ( r ) = S m ( Γ [ r ] ) 1 , w m ( r ) = S m ( Γ [ r ] ) 3 w_m(r)=S_m(\Gamma[r])_3 w m ( r ) = S m ( Γ [ r ] ) 3 .
Let Inv a , b ( f ) \operatorname{Inv}_{a,b}(f) Inv a , b ( f ) denote Lean's total choice inverse
invFunOn f [ a , b ] \operatorname{invFunOn}f\,[a,b] invFunOn f [ a , b ] . For
a = 2 ( m + 1 + β ) a=2(m+1+\beta) a = 2 ( m + 1 + β ) , b = 2 ( m + 2 − β ) b=2(m+2-\beta) b = 2 ( m + 2 − β ) , define
g m = Inv a , b ( ϕ m ) , h m ( y ) = 2 / g m ( y ) . g_m=\operatorname{Inv}_{a,b}(\phi_m),\qquad h_m(y)=2/g_m(y). g m = Inv a , b ( ϕ m ) , h m ( y ) = 2/ g m ( y ) .
Write γ n ( y ) = 1 / ( n + y ) \gamma_n(y)=1/(n+y) γ n ( y ) = 1/ ( n + y ) for the Gauss inverse branch.
The retained phase set is
H N = ⋃ m < N ( h m ( 1 − 2 β ) , h m ( 2 β ) ) \mathcal H_N=\bigcup_{m<N}(h_m(1-2\beta),h_m(2\beta)) H N = ⋃ m < N ( h m ( 1 − 2 β ) , h m ( 2 β )) .
Write x ( Y ) = Ξ ( e + ( Y ) ) x(Y)=\Xi(e_+(Y)) x ( Y ) = Ξ ( e + ( Y )) , Φ t s ( x ) = α x , s ( t ) \Phi^s_t(x)=\alpha_{x,s}(t) Φ t s ( x ) = α x , s ( t ) and I ( x , s ) I(x,s) I ( x , s )
for its maximal domain. Set Y j = G j X Y_j=G^jX Y j = G j X , Z = F ( Y m ) Z=F(Y_m) Z = F ( Y m ) ,
N m ( X ) = ( R m ( X ) , S m ( X ) 1 , S m ( X ) 3 ) N_m(X)=(R_m(X),S_m(X)_1,S_m(X)_3) N m ( X ) = ( R m ( X ) , S m ( X ) 1 , S m ( X ) 3 ) , and
d m ( X ) = ∑ j < m t G ( Y j ) + T ( Y m ) + t ∗ ( Z ) . d_m(X)=\sum_{j<m}t_G(Y_j)+T(Y_m)+t_*(Z). d m ( X ) = j < m ∑ t G ( Y j ) + T ( Y m ) + t ∗ ( Z ) .
The six axis frames realize all permutations of the normalized walls
and diagonal shears. Write L m L_m L m for the frame obtained by m m m swaps
followed by the cyclic permutation.
The event itinerary I m ( X ) \mathcal I_m(X) I m ( X ) has the following meaning.
For j ≤ m j\le m j ≤ m , the radius of Y j Y_j Y j exceeds two, the entry is an upward
unit-wall crossing, its core first return is valid, and its endpoint
is e − ( F ( Y j ) ) e_-(F(Y_j)) e − ( F ( Y j )) . For j < m j<m j < m the exit radius exceeds four, and the
first positive unit-wall hit in the swapped chart reaches e + ( Y j + 1 ) e_+(Y_{j+1}) e + ( Y j + 1 ) ,
the reflection of the endpoint at time t G ( Y j ) t_G(Y_j) t G ( Y j ) . The final exit has
radius strictly between two and four. In the cycled exit chart its
first positive unit-wall hit occurs at t ∗ ( Z ) t_*(Z) t ∗ ( Z ) , has state S ∗ ( Z ) S_*(Z) S ∗ ( Z )
and positive event rate. Finally ⌊ X 0 / 2 ⌋ = m + 1 \lfloor X_0/2\rfloor=m+1 ⌊ X 0 /2 ⌋ = m + 1 .
For a budget cap b b b define A m ( b ) A_m(b) A m ( b ) by the conditions on ( B , X ) (B,X) ( B , X )
0 < B ≤ b , m < ⌊ B − σ ⌋ , X 1 , X 2 > 0 , X 1 + X 2 ≤ B , m + 1 + B σ ≤ X 0 / 2 ≤ m + 2 − B σ . 0<B\le b,\quad m<\lfloor B^{-\sigma}\rfloor,\quad X_1,X_2>0,\quad
X_1+X_2\le B,\quad m+1+B^\sigma\le X_0/2\le m+2-B^\sigma. 0 < B ≤ b , m < ⌊ B − σ ⌋ , X 1 , X 2 > 0 , X 1 + X 2 ≤ B , m + 1 + B σ ≤ X 0 /2 ≤ m + 2 − B σ .
The selected domain D m ( b ) D_m(b) D m ( b ) additionally requires
2 B σ < P m ( X ) < 1 − 2 B σ 2B^\sigma<P_m(X)<1-2B^\sigma 2 B σ < P m ( X ) < 1 − 2 B σ ; the budget return is
F m ( B , X ) = ( B 4 / 3 , N m ( X ) ) \mathcal F_m(B,X)=(B^{4/3},N_m(X)) F m ( B , X ) = ( B 4/3 , N m ( X )) .
In a small-budget assertion there exists 0 < δ ≤ 1 / 40000 0<\delta\le1/40000 0 < δ ≤ 1/40000 such
that for every 0 < η ≤ δ 0<\eta\le\delta 0 < η ≤ δ , J ∈ N J\in\mathbb N J ∈ N with J ≥ 20 J\ge20 J ≥ 20 ,
0 < σ < 1 0<\sigma<1 0 < σ < 1 and 2 J σ < 1 2J\sigma<1 2 J σ < 1 , the stated constants can be chosen.
Let p p p be a budget and core state surviving all selected returns at
cap b b b . Its successive digits are a n a_n a n , its transported states are
X n X_n X n , its phases are y n = 2 / ( X n ) 0 y_n=2/(X_n)_0 y n = 2/ ( X n ) 0 , and m n = a n − 1 m_n=a_n-1 m n = a n − 1 . Put
d n = d m n ( X n ) , s n = ∑ j < n d j , A 0 = 1 , A n + 1 = L m n A n . d_n=d_{m_n}(X_n),\qquad s_n=\sum_{j<n}d_j,\qquad
A_0=1,\quad A_{n+1}=L_{m_n}A_n. d n = d m n ( X n ) , s n = j < n ∑ d j , A 0 = 1 , A n + 1 = L m n A n .
Frame indices use the chosen composition on the six labels. For restart
data w = ( ( i , s ) , ( B , X ) ) w=((i,s),(B,X)) w = (( i , s ) , ( B , X )) , let t n = s + s n t_n=s+s_n t n = s + s n and let P n P_n P n denote the
frame with index chosen for A n Q i A_n Q_i A n Q i , where Q i Q_i Q i is the initial
frame of label i i i . A restart witness for x x x requires
s > 0 s>0 s > 0 , s ∈ I ( x , 0 ) s\in I(x,0) s ∈ I ( x , 0 ) and a survivor with initial data ( B , X ) (B,X) ( B , X ) ,
full era statistics, and entry e + ( X ) = Π ( Q i Φ s 0 ( x ) ) e_+(X)=\Pi(Q_i\Phi^0_s(x)) e + ( X ) = Π ( Q i Φ s 0 ( x )) .
Let λ \lambda λ be Lebesgue measure on R \mathbb R R , and let
λ 0 \lambda_0 λ 0 be its restriction to ( 0 , 1 ) (0,1) ( 0 , 1 ) . The Gauss measure is
d μ G ( x ) = 1 log 2 ( 1 + x ) d λ 0 ( x ) . d\mu_G(x)=\frac{1}{\log2\,(1+x)}\,d\lambda_0(x). d μ G ( x ) = log 2 ( 1 + x ) 1 d λ 0 ( x ) .
Write w ( x ) = 1 / ( log 2 ( 1 + x ) ) w(x)=1/(\log2\,(1+x)) w ( x ) = 1/ ( log 2 ( 1 + x )) and P ( x ) = log ( 1 + x ) / log 2 P(x)=\log(1+x)/\log2 P ( x ) = log ( 1 + x ) / log 2 for x ≥ 0 x\geq0 x ≥ 0 .
Let G ( x ) = 1 / x − ⌊ 1 / x ⌋ G(x)=1/x-\lfloor1/x\rfloor G ( x ) = 1/ x − ⌊ 1/ x ⌋ for x ≠ 0 x\ne0 x = 0 , with G ( 0 ) = 0 G(0)=0 G ( 0 ) = 0 .
For a finite word w = ( a 0 , … , a k − 1 ) w=(a_0,\ldots,a_{k-1}) w = ( a 0 , … , a k − 1 ) of natural numbers, set
C w = ( g a 0 ∘ ⋯ ∘ g a k − 1 ) ( ( 0 , 1 ) ) , g a ( t ) = 1 / ( a + t ) , C_w=(g_{a_0}\circ\cdots\circ g_{a_{k-1}})((0,1)),\qquad
g_a(t)=1/(a+t), C w = ( g a 0 ∘ ⋯ ∘ g a k − 1 ) (( 0 , 1 )) , g a ( t ) = 1/ ( a + t ) ,
where the empty composition is the identity and 0 − 1 = 0 0^{-1}=0 0 − 1 = 0 . Define
f w = 1 C w , m w = μ G ( C w ) , B G = { x ∈ R : ∀ w , 1 n ∑ j = 0 n − 1 f w ( G j x ) ⟶ m w } . f_w=\mathbf1_{C_w},\qquad m_w=\mu_G(C_w),\qquad
\mathcal B_G=\left\{x\in\mathbb R:\ \forall w,\
\frac1n\sum_{j=0}^{n-1}f_w(G^jx)\longrightarrow m_w\right\}. f w = 1 C w , m w = μ G ( C w ) , B G = { x ∈ R : ∀ w , n 1 j = 0 ∑ n − 1 f w ( G j x ) ⟶ m w } .
For a positive-digit sequence a a a , write π ( a ) \pi(a) π ( a ) for its continued-fraction
code, σ j a \sigma^j a σ j a for its tail beginning at j j j , and a ∣ k a|_k a ∣ k for its first
k k k digits.
Define the natural-valued digit, tail observables, and truncations by
D ( x ) = ⌊ 1 / x ⌋ N , H k ( x ) = 1 ( 0 , 1 / k ) ( x ) ( k ≥ 1 ) , D R ( x ) = min ( D ( x ) , R ) ( R ∈ N ) . D(x)=\lfloor1/x\rfloor_{\mathbb N},\qquad
H_k(x)=\mathbf1_{(0,1/k)}(x)\quad(k\geq1),\qquad
D_R(x)=\min(D(x),R)\quad(R\in\mathbb N). D ( x ) = ⌊ 1/ x ⌋ N , H k ( x ) = 1 ( 0 , 1/ k ) ( x ) ( k ≥ 1 ) , D R ( x ) = min ( D ( x ) , R ) ( R ∈ N ) .
Here the natural floor is zero for negative arguments, and 0 − 1 = 0 0^{-1}=0 0 − 1 = 0 .
Write
p k = log ( ( k + 1 ) 2 / ( k ( k + 2 ) ) ) log 2 , q k = log ( 1 + 1 / k ) log 2 , t R = log ( R + 1 ) log 2 . p_k=\frac{\log((k+1)^2/(k(k+2)))}{\log2},\qquad
q_k=\frac{\log(1+1/k)}{\log2},\qquad
t_R=\frac{\log(R+1)}{\log2}. p k = log 2 log (( k + 1 ) 2 / ( k ( k + 2 ))) , q k = log 2 log ( 1 + 1/ k ) , t R = log 2 log ( R + 1 ) .
For a real sequence u u u , define
A n ( u ) = 1 n ∑ j = 0 n − 1 u j ( n ≥ 1 ) , A 0 ( u ) = 0. A_n(u)=\frac1n\sum_{j=0}^{n-1}u_j\quad(n\geq1),\qquad A_0(u)=0. A n ( u ) = n 1 j = 0 ∑ n − 1 u j ( n ≥ 1 ) , A 0 ( u ) = 0.
For a positive-digit sequence a a a and a real sequence y y y , let
E ( a , y ) \mathcal E(a,y) E ( a , y ) mean all of the following statements:
A N ( f ∘ y ) → ∫ f d μ G for every f : R → R continuous on [ 0 , 1 ] , A_N(f\circ y)\to\int f\,d\mu_G
\quad\text{for every }f:\mathbb R\to\mathbb R
\text{ continuous on }[0,1], A N ( f ∘ y ) → ∫ f d μ G for every f : R → R continuous on [ 0 , 1 ] ,
A N ( j ↦ 1 { ( σ j a ) ∣ ∣ w ∣ = w } ) → m w for every finite positive-digit word w , A_N(j\mapsto\mathbf1_{\{(\sigma^ja)|_{|w|}=w\}})\to m_w
\quad\text{for every finite positive-digit word }w, A N ( j ↦ 1 {( σ j a ) ∣ ∣ w ∣ = w } ) → m w for every finite positive-digit word w ,
A N ( j ↦ 1 { a j = k } ) → p k , A N ( j ↦ 1 { k ≤ a j } ) → q k ( k ≥ 1 ) , A_N(j\mapsto\mathbf1_{\{a_j=k\}})\to p_k,\qquad
A_N(j\mapsto\mathbf1_{\{k\leq a_j\}})\to q_k\quad(k\geq1), A N ( j ↦ 1 { a j = k } ) → p k , A N ( j ↦ 1 { k ≤ a j } ) → q k ( k ≥ 1 ) ,
A N ( j ↦ min ( a j , R ) ) → t R ( R ∈ N ) , A N ( j ↦ a j ) → + ∞ . A_N(j\mapsto\min(a_j,R))\to t_R\quad(R\in\mathbb N),\qquad
A_N(j\mapsto a_j)\to+\infty. A N ( j ↦ min ( a j , R )) → t R ( R ∈ N ) , A N ( j ↦ a j ) → + ∞.
Let w w w be restart data, p p p a survivor and x x x a constraint-one state.
Suppose the survivor digits and phases satisfy E \mathcal E E , every
I m n ( X n ) \mathcal I_{m_n}(X_n) I m n ( X n ) holds with e + ( X n + 1 ) = S m n ( X n ) e_+(X_{n+1})=S_{m_n}(X_n) e + ( X n + 1 ) = S m n ( X n ) ,
the t n t_n t n increase strictly to + ∞ +\infty + ∞ , and for all n n n one has
t n > 0 t_n>0 t n > 0 and Ξ ( e + ( X n ) ) = P n Φ t n 0 ( x ) \Xi(e_+(X_n))=P_n\Phi^0_{t_n}(x) Ξ ( e + ( X n )) = P n Φ t n 0 ( x ) .
Then
( a n + 1 , X n + 1 , t n + 1 , P n + 1 ) n ≥ 0 (a_{n+1},X_{n+1},t_{n+1},P_{n+1})_{n\ge0} ( a n + 1 , X n + 1 , t n + 1 , P n + 1 ) n ≥ 0
is a physical era sequence on the original trajectory: it retains the
statistics, entrance identities and event blocks, the next state, time
and frame agree with the actual return, and its first entrance is the
terminal arrival of an earlier complete block.