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Inproof theory,ordinal analysis assignsordinals (oftenlarge countable ordinals) to mathematical theories as a measure of their strength. If theories have the same proof-theoretic ordinal they are oftenequiconsistent, and if one theory has a larger proof-theoretic ordinal than another it can often prove the consistency of the second theory.

In addition to obtaining the proof-theoretic ordinal of a theory, in practice ordinal analysis usually also yields various other pieces of information about the theory being analyzed, for example characterizations of the classes of provably recursive,hyperarithmetical, or${\displaystyle {\mathrm{\Delta }}_2^1}$ functions of the theory.^[1]

The field of ordinal analysis was formed whenGerhard Gentzen in 1934 usedcut elimination to prove, in modern terms, that theproof-theoretic ordinal ofPeano arithmetic isε₀. SeeGentzen's consistency proof.

Ordinal analysis concerns true, effective (recursive) theories that can interpret a sufficient portion of arithmetic to make statements aboutordinal notations.

Theproof-theoretic ordinal of such a theory${\displaystyle T}$ is the supremum of theorder types of allordinal notations (necessarilyrecursive, see next section) that the theory can prove arewell founded—the supremum of all ordinals${\displaystyle \alpha }$ for which there exists anotation${\displaystyle o}$ in Kleene's sense such that${\displaystyle T}$ proves that${\displaystyle o}$ is an ordinal notation. Equivalently, it is the supremum of all ordinals${\displaystyle \alpha }$ such that there exists arecursive relation${\displaystyle R}$ on${\displaystyle \omega }$ (the set of natural numbers) thatwell-orders it with ordinal${\displaystyle \alpha }$ and such that${\displaystyle T}$ provestransfinite induction of arithmetical statements for${\displaystyle R}$.

Some theories, such as subsystems ofsecond-order arithmetic (Z₂), have no conceptualization or way to make arguments about transfinite ordinals. For example, to formalize what it means for a subsystem${\displaystyle T}$ of Z₂ to "prove${\displaystyle \alpha }$ well-ordered", we instead construct anordinal notation with order type${\displaystyle \alpha }$.${\displaystyle T}$ can now work with various transfinite induction principles along, which substitute for reasoning about set-theoretic ordinals.

However, some pathological notation systems exist that are unexpectedly difficult to work with. For example, Rathjen gives aprimitive recursive notation system that is well-founded if and only if PA is consistent,^[2]p. 3 despite having order type${\displaystyle \omega }$. Including such a notation in the ordinal analysis of PA would result in the false equality${\displaystyle \mathsf{P}\mathsf{T}\mathsf{O}\mathsf{(}\mathsf{P}\mathsf{A}\mathsf{)}=\omega }$.

Since an ordinal notation must be recursive, the proof-theoretic ordinal of any theory is less than or equal to theChurch–Kleene ordinal${\displaystyle {\omega }_1^{\mathrm{C}\mathrm{K}}}$. In particular, the proof-theoretic ordinal of aninconsistent theory is equal to${\displaystyle {\omega }_1^{\mathrm{C}\mathrm{K}}}$, because an inconsistent theory trivially proves that all ordinal notations are well-founded.

For any theory that's both${\displaystyle {\mathrm{\Sigma }}_1^1}$-axiomatizable and${\displaystyle {\mathrm{\Pi }}_1^1}$-sound, the existence of a recursive ordering that the theory fails to prove is well-ordered follows from the${\displaystyle {\mathrm{\Sigma }}_1^1}$ bounding theorem, and said provably well-founded ordinal notations are in fact well-founded by${\displaystyle {\mathrm{\Pi }}_1^1}$-soundness. Thus the proof-theoretic ordinal of a${\displaystyle {\mathrm{\Pi }}_1^1}$-sound theory that has a${\displaystyle {\mathrm{\Sigma }}_1^1}$ axiomatization will always be a (countable)recursive ordinal, that is, strictly less than${\displaystyle {\omega }_1^{\mathrm{C}\mathrm{K}}}$.^{[2]Theorem 2.21}

• Q,Robinson arithmetic (although the definition of the proof-theoretic ordinal for such weak theories has to be tweaked)^{[citation needed]}.
• PA^–, the first-order theory of the nonnegative part of a discretelyordered ring.

• RFA,rudimentary function arithmetic.^[3]
• IΔ₀, arithmetic with induction on Δ₀-predicates without any axiom asserting that exponentiation is total.

• EFA,elementary function arithmetic.
• IΔ₀ + exp, arithmetic with induction on Δ₀-predicates augmented by an axiom asserting that exponentiation is total.
• RCA^*
  ₀, a second-order form of EFA sometimes used inreverse mathematics.
• WKL^*
  ₀, a second-order form of EFA sometimes used inreverse mathematics.

Friedman'sgrand conjecture suggests that much "ordinary" mathematics can be proved in weak systems having this as their proof-theoretic ordinal.

• IΔ₀ or EFA augmented by an axiom ensuring that each element of then-th level${\displaystyle {\mathcal{E}}^n}$ of theGrzegorczyk hierarchy is total.

• RCA₀,recursive comprehension.
• WKL₀,weak Kőnig's lemma.
• PRA,primitive recursive arithmetic.
• IΣ₁, arithmetic with induction on Σ₁-predicates.

• PA,Peano arithmetic (shown byGentzen usingcut elimination).
• ACA₀,arithmetical comprehension.

• ATR₀,arithmetical transfinite recursion.
• Martin-Löf type theory with arbitrarily many finite level universes.

This ordinal is sometimes considered to be the upper limit for "predicative" theories.

• ID₁, the firsttheory of inductive definitions.
• KP,Kripke–Platek set theory with theaxiom of infinity.
• CZF, Aczel'sconstructive Zermelo–Fraenkel set theory.
• EON, a weak variant of theFeferman's explicit mathematics system T₀.

The Kripke–Platek or CZF set theories are weak set theories without axioms for the full powerset given as set of all subsets. Instead, they tend to either have axioms of restricted separation and formation of new sets, or they grant existence of certain function spaces (exponentiation) instead of carving them out from bigger relations.

• ${\displaystyle {\mathrm{\Pi }}_1^1\text{-}{\mathsf{C}\mathsf{A}}_0}$,Π₁¹ comprehension has a rather large proof-theoretic ordinal, which was described byTakeuti in terms of "ordinal diagrams",^[5]p. 13 and which is bounded byψ₀(Ω_ω) inBuchholz's notation. It is also the ordinal of, the theory of finitely iterated inductive definitions. And also the ordinal of MLW, Martin-Löf type theory with indexed W-TypesSetzer (2004).
• ID_ω, thetheory of ω-iterated inductive definitions. Its proof-theoretic ordinal is equal to theTakeuti–Feferman–Buchholz ordinal.
• T₀, Feferman's constructive system of explicit mathematics has a larger proof-theoretic ordinal, which is also the proof-theoretic ordinal of the KPi, Kripke–Platek set theory with iterated admissibles and${\displaystyle {\mathrm{\Sigma }}_2^1\text{-}\mathsf{A}\mathsf{C}+\mathsf{B}\mathsf{I}}$.
• KPi, an extension ofKripke–Platek set theory based on arecursively inaccessible ordinal, has a very large proof-theoretic ordinal${\displaystyle \psi ({\epsilon }_{I+1})}$ described in a 1983 paper of Jäger and Pohlers, where I is the smallest inaccessible.^[6] This ordinal is also the proof-theoretic ordinal of${\displaystyle {\mathrm{\Delta }}_2^1\text{-}\mathsf{C}\mathsf{A}+\mathsf{B}\mathsf{I}}$.
• KPM, an extension ofKripke–Platek set theory based on arecursively Mahlo ordinal, has a very large proof-theoretic ordinal θ, which was described byRathjen (1990).
• TTM, an extension of Martin-Löf type theory by one Mahlo-universe, has an even larger proof-theoretic ordinal${\displaystyle {\psi }_{{\mathrm{\Omega }}_1}({\mathrm{\Omega }}_{M+\omega })}$.
• ${\displaystyle \mathsf{K}\mathsf{P}+{\mathrm{\Pi }}_3-Ref}$ has a proof-theoretic ordinal equal to${\displaystyle \mathrm{\Psi }({\epsilon }_{K+1})}$, where${\displaystyle K}$ refers to the first weakly compact, due to (Rathjen 1993)
• ${\displaystyle \mathsf{K}\mathsf{P}+{\mathrm{\Pi }}_{\omega }-Ref}$ has a proof-theoretic ordinal equal to${\displaystyle {\mathrm{\Psi }}_X^{{\epsilon }_{\mathrm{\Xi }+1}}}$, where${\displaystyle \mathrm{\Xi }}$ refers to the first${\displaystyle {\mathrm{\Pi }}_0^2}$-indescribable and${\displaystyle \mathbb{X}=({\omega }^{+};P_0;ϵ,ϵ,0)}$, due to (Stegert 2010).
• ${\displaystyle \mathsf{S}\mathsf{t}\mathsf{a}\mathsf{b}\mathsf{i}\mathsf{l}\mathsf{i}\mathsf{t}\mathsf{y}}$ has a proof-theoretic ordinal equal to${\displaystyle {\mathrm{\Psi }}_{\mathbb{X}}^{{\epsilon }_{\mathrm{{\rm Y}}+1}}}$ where${\displaystyle \mathrm{{\rm Y}}}$ is a cardinal analogue of the least ordinal${\displaystyle \alpha }$ which is${\displaystyle (\alpha +\beta )}$-stable for all and${\displaystyle \mathbb{X}=({\omega }^{+};P_0;ϵ,ϵ,0)}$, due to (Stegert 2010).

Most theories capable of describing the power set of the natural numbers have proof-theoretic ordinals that are so large that no explicit combinatorial description has yet been given. This includes${\displaystyle {\mathrm{\Pi }}_2^1-C{A}_0}$, fullsecond-order arithmetic (${\displaystyle {\mathrm{\Pi }}_{\mathrm{\infty }}^1-C{A}_0}$) and set theories with powersets includingZF and ZFC.^[7] The strength ofintuitionistic ZF (IZF) equals that of ZF.

Table of proof-theoretic ordinals

Ordinal	First-order arithmetic	Second-order arithmetic	Kripke–Platek set theory	Type theory	Constructive set theory	Explicit mathematics
${\displaystyle \omega }$	${\displaystyle \mathsf{Q}}$,${\displaystyle {\mathsf{P}\mathsf{A}}^{-}}$
${\displaystyle {\omega }^2}$	${\displaystyle \mathsf{R}\mathsf{F}\mathsf{A}}$,${\displaystyle {\mathsf{I}\mathsf{\Delta }}_0}$
${\displaystyle {\omega }^3}$	${\displaystyle \mathsf{E}\mathsf{F}\mathsf{A}}$,${\displaystyle {\mathsf{I}\mathsf{\Delta }}_0^{\mathsf{+}}}$,${\displaystyle \mathsf{B}{\mathrm{\Sigma }}_1}$[8]Theorem 4.1	${\displaystyle {\mathsf{R}\mathsf{C}\mathsf{A}}_0^{\ast }}$,${\displaystyle {\mathsf{W}\mathsf{K}\mathsf{L}}_0^{\ast }}$
${\displaystyle {\omega }^n}$[1]	${\displaystyle {\mathsf{E}\mathsf{F}\mathsf{A}}^{\mathsf{n}}}$,${\displaystyle {\mathsf{I}\mathsf{\Delta }}_0^{\mathsf{n}\mathsf{+}}}$
${\displaystyle {\omega }^{\omega }}$	${\displaystyle \mathsf{P}\mathsf{R}\mathsf{A}}$,${\displaystyle {\mathsf{I}\mathsf{\Sigma }}_1}$[9]p. 13	${\displaystyle {\mathsf{R}\mathsf{C}\mathsf{A}}_0}$[9]p. 13,${\displaystyle {\mathsf{W}\mathsf{K}\mathsf{L}}_0}$[9]p. 13		${\displaystyle \mathsf{C}\mathsf{P}\mathsf{R}\mathsf{C}}$
${\displaystyle {\omega }^{{\omega }^{{\omega }^{\omega }}}}$	${\displaystyle \mathsf{I}{\mathrm{\Sigma }}_3}$[10][9]p. 13	${\displaystyle {\mathsf{R}\mathsf{C}\mathsf{A}}_0+({\mathrm{\Pi }}_2^0{)}^{-}\mathsf{-}\mathsf{I}\mathsf{N}\mathsf{D}}$[11]: 40
${\displaystyle {\epsilon }_0}$	${\displaystyle \mathsf{P}\mathsf{A}}$[9]p. 13	${\displaystyle {\mathsf{A}\mathsf{C}\mathsf{A}}_0}$[9]p. 13,${\displaystyle {\mathsf{\Sigma }}_1^1{\mathsf{-}\mathsf{A}\mathsf{C}}_0}$[9]p. 13,${\displaystyle \text{R-}\widehat{\mathbf{E}\mathbf{\Omega }}}$[12]p. 8,${\displaystyle \mathsf{R}\mathsf{C}\mathsf{A}}$[13]p. 148,${\displaystyle \mathsf{W}\mathsf{K}\mathsf{L}}$[13]p. 148,${\displaystyle {\mathsf{\Delta }}_1^1{\mathsf{-}\mathsf{C}\mathsf{A}}_0}$[14]	${\displaystyle {\mathrm{K}\mathrm{P}\mathrm{u}}^r}$[15]p. 869			${\displaystyle {\mathsf{E}\mathsf{M}}_0}$
${\displaystyle {\epsilon }_{\omega }}$		${\displaystyle {\mathsf{A}\mathsf{C}\mathsf{A}}_0+\mathsf{i}\mathsf{R}\mathsf{T}}$,[16]${\displaystyle {\mathsf{R}\mathsf{C}\mathsf{A}}_0+\mathrm{\forall }Y\mathrm{\forall }n\mathrm{\exists }X(\text{TJ}(n,X,Y))}$[17]: 8
${\displaystyle {\epsilon }_{{\epsilon }_0}}$		${\displaystyle \mathsf{A}\mathsf{C}\mathsf{A}}$[18]p. 959
${\displaystyle {\zeta }_0}$		${\displaystyle {\mathsf{A}\mathsf{C}\mathsf{A}}_0+\mathrm{\forall }X\mathrm{\exists }Y(\text{TJ}(\omega ,X,Y))}$,[19][17]${\displaystyle {\mathsf{p}}_1({\mathsf{A}\mathsf{C}\mathsf{A}}_0)}$,[20]: 7 ${\displaystyle {\mathsf{R}\mathsf{F}\mathsf{N}}_0}$[19]p. 17,${\displaystyle {\mathsf{A}\mathsf{C}\mathsf{A}}_0+(\mathsf{B}\mathsf{R})}$[19]p. 5
${\displaystyle \phi (2,{\epsilon }_0)}$		${\displaystyle \mathsf{R}\mathsf{F}\mathsf{N}}$,${\displaystyle \mathsf{A}\mathsf{C}\mathsf{A}+\mathrm{\forall }X\mathrm{\exists }Y(\text{TJ}(\omega ,X,Y))}$[19]p. 52
${\displaystyle \phi (\omega ,0)}$	${\displaystyle {\mathsf{I}\mathsf{D}}_1\mathrm{\#}}$,${\displaystyle {\mathsf{T}\mathsf{I}\mathsf{D}}_0}$[21]p. 137	${\displaystyle {\mathsf{\Delta }}_1^1\mathsf{-}\mathsf{C}\mathsf{R}}$,${\displaystyle {\mathrm{\Sigma }}_1^1{\mathsf{-}\mathsf{D}\mathsf{C}}_0}$[22]				${\displaystyle {\mathsf{E}\mathsf{M}}_0\mathsf{+}\mathsf{J}\mathsf{R}}$
${\displaystyle \phi ({\epsilon }_0,0)}$	${\displaystyle {\widehat{\mathsf{I}\mathsf{D}}}_1}$,${\displaystyle \mathsf{K}\mathsf{F}\mathsf{L}}$[23]p. 17,${\displaystyle \mathsf{K}\mathsf{F}}$[23]p. 17	${\displaystyle {\mathsf{\Delta }}_1^1\mathsf{-}\mathsf{C}\mathsf{A}}$[24]p. 140,${\displaystyle {\mathsf{\Sigma }}_1^1\mathsf{-}\mathsf{A}\mathsf{C}}$[24]p. 140,${\displaystyle {\mathsf{\Sigma }}_1^1\mathsf{-}\mathsf{D}\mathsf{C}}$[24]p. 140,${\displaystyle \text{W-}\widehat{\mathbf{E}\mathbf{\Omega }}}$[12]p. 8	${\displaystyle {\mathrm{K}\mathrm{P}\mathrm{u}}^r+({\mathrm{I}\mathrm{N}\mathrm{D}}_N)}$[15]p. 870	${\displaystyle {\mathsf{M}\mathsf{L}}_1}$		${\displaystyle {\mathsf{E}\mathsf{M}}_0\mathsf{+}\mathsf{J}}$
${\displaystyle \phi ({\epsilon }_{{\epsilon }_0},0)}$		${\displaystyle \widehat{\mathbf{E}\mathbf{\Omega }}}$[12]p. 27,${\displaystyle {\widehat{\mathbf{E}\mathbf{I}\mathbf{D}}}_{\mathbf{1}}}$[12]p. 27
${\displaystyle \phi (\phi (\omega ,0),0)}$	${\displaystyle \mathrm{P}\mathrm{R}\mathrm{S}\omega }$[25]p. 9
[2]	${\displaystyle \mathsf{A}\mathsf{u}\mathsf{t}\mathsf{(}\mathsf{I}\mathsf{D}\mathsf{\#}\mathsf{)}}$
${\displaystyle {\mathrm{\Gamma }}_0}$	,[26]${\displaystyle \mathsf{U}\mathsf{(}\mathsf{P}\mathsf{A}\mathsf{)}}$,${\displaystyle {\mathbf{K}\mathbf{F}\mathbf{L}}^{\ast }}$[23]p. 22,${\displaystyle {\mathbf{K}\mathbf{F}}^{\ast }}$[23]p. 22,${\displaystyle \mathcal{U}(\mathrm{N}\mathrm{F}\mathrm{A})}$,[27]${\displaystyle {\mathsf{T}\mathsf{I}\mathsf{D}}_0^{+}}$[21]p. 137	${\displaystyle {\mathsf{A}\mathsf{T}\mathsf{R}}_0}$,${\displaystyle {\mathsf{\Delta }}_1^1\mathsf{-}\mathsf{C}\mathsf{A}\mathsf{+}\mathsf{B}\mathsf{R}}$,${\displaystyle {\mathrm{\Delta }}_1^1{-\mathrm{C}\mathrm{A}}_0+(\mathrm{S}\mathrm{U}\mathrm{B})}$,[28]${\displaystyle {\mathrm{F}\mathrm{P}}_0}$[29]p. 26	${\displaystyle {\mathsf{K}\mathsf{P}\mathsf{i}}^0}$[15]p. 878,${\displaystyle {\mathsf{K}\mathsf{P}\mathsf{u}}^0+(\mathrm{B}\mathrm{R})}$[15]p. 878	,${\displaystyle \mathsf{M}\mathsf{L}\mathsf{U}}$
${\displaystyle {\mathrm{\Gamma }}_{{\omega }^{\omega }}}$			${\displaystyle {\mathsf{K}\mathsf{P}\mathsf{I}}^0+({{\mathsf{\Sigma }}_{\mathsf{1}}\mathsf{-}\mathsf{I}}_{\omega })}$[30]p. 13
${\displaystyle {\mathrm{\Gamma }}_{{\epsilon }_0}}$	${\displaystyle {\widehat{\mathsf{I}\mathsf{D}}}_{\omega }}$	${\displaystyle \mathsf{A}\mathsf{T}\mathsf{R}}$[31]	${\displaystyle {\mathsf{K}\mathsf{P}\mathsf{I}}^0{\mathsf{+}\mathsf{F}\mathsf{-}\mathsf{I}}_{\omega }}$
${\displaystyle \phi (1,\omega ,0)}$		${\displaystyle {\mathsf{A}\mathsf{T}\mathsf{R}}_0+({\mathsf{\Sigma }}_1^1\mathsf{-}\mathsf{D}\mathsf{C})}$[20]: 7	${\displaystyle {\mathsf{K}\mathsf{P}\mathsf{i}}^0{\mathsf{+}{\mathsf{\Sigma }}_{\mathsf{1}}\mathsf{-}\mathsf{I}}_{\omega }}$
${\displaystyle \phi (1,{\epsilon }_0,0)}$		${\displaystyle \mathsf{A}\mathsf{T}\mathsf{R}+({\mathsf{\Sigma }}_1^1\mathsf{-}\mathsf{D}\mathsf{C})}$[20]: 7	${\displaystyle {\mathsf{K}\mathsf{P}\mathsf{i}}^0{\mathsf{+}\mathsf{F}\mathsf{-}\mathsf{I}}_{\omega }}$
${\displaystyle \phi (1,{\mathrm{\Gamma }}_0,0)}$				${\displaystyle \mathsf{M}\mathsf{L}\mathsf{S}}$
${\displaystyle \phi (2,0,0)}$	${\displaystyle \mathsf{A}\mathsf{u}\mathsf{t}\mathsf{(}\widehat{\mathsf{I}\mathsf{D}}\mathsf{)}}$,${\displaystyle {\mathsf{F}\mathsf{T}\mathsf{R}}_0}$[32]	${\displaystyle A{x}_{{\mathrm{\Sigma }}_1^1\mathsf{-}\mathsf{A}\mathsf{C}}{\mathsf{T}\mathsf{R}}_0}$[33]p. 1167,${\displaystyle A{x}_{\mathsf{A}\mathsf{T}\mathsf{R}+{\mathrm{\Sigma }}_1^1\mathsf{-}\mathsf{D}\mathsf{C}}{\mathsf{R}\mathsf{F}\mathsf{N}}_0}$[33]p. 1167	${\displaystyle {\mathsf{K}\mathsf{P}\mathsf{h}}^0}$	${\displaystyle \mathsf{A}\mathsf{u}\mathsf{t}\mathsf{(}\mathsf{M}\mathsf{L}\mathsf{)}}$
${\displaystyle \phi (2,0,{\epsilon }_0)}$	${\displaystyle \mathsf{F}\mathsf{T}\mathsf{R}}$[32]	${\displaystyle A{x}_{{\mathrm{\Sigma }}_1^1\mathsf{-}\mathsf{A}\mathsf{C}}\mathsf{T}\mathsf{R}}$[33]p. 1167,${\displaystyle A{x}_{\mathsf{A}\mathsf{T}\mathsf{R}+{\mathrm{\Sigma }}_1^1\mathsf{-}\mathsf{D}\mathsf{C}}\mathsf{R}\mathsf{F}\mathsf{N}}$[33]p. 1167
${\displaystyle \phi (2,{\epsilon }_0,0)}$			${\displaystyle {\mathsf{K}\mathsf{P}\mathsf{h}}_0+({\mathsf{F}\mathsf{-}\mathsf{I}}_{\omega })}$[32]: 11
${\displaystyle \phi (\omega ,0,0)}$		${\displaystyle ({\mathrm{\Pi }}_2^1\mathsf{-}\mathsf{R}\mathsf{F}\mathsf{N}{)}_0^{{\mathrm{\Sigma }}_1^1\mathsf{-}\mathsf{D}\mathsf{C}}}$[34]p. 233,${\displaystyle {\mathrm{\Sigma }}_1^1{\mathsf{-}\mathsf{T}\mathsf{D}\mathsf{C}}_0}$[34]p. 233	${\displaystyle {\mathsf{K}\mathsf{P}\mathsf{m}}^0}$[35]p. 276	${\displaystyle \mathsf{E}\mathsf{M}\mathsf{A}}$[35]p. 276
${\displaystyle \phi ({\epsilon }_0,0,0)}$		${\displaystyle ({\mathrm{\Pi }}_2^1\mathsf{-}\mathsf{R}\mathsf{F}\mathsf{N}{)}^{{\mathrm{\Sigma }}_1^1\mathsf{-}\mathsf{D}\mathsf{C}}}$[34]p. 233,${\displaystyle {\mathrm{\Sigma }}_1^1\mathsf{-}\mathsf{T}\mathsf{D}\mathsf{C}}$[20]	${\displaystyle {\mathsf{K}\mathsf{P}\mathsf{m}}^0+({\mathcal{L}}^{\ast }{\mathsf{-}\mathsf{I}}_{\mathsf{N}})}$[35]p. 277	${\displaystyle \mathsf{E}\mathsf{M}\mathsf{A}+(\mathbb{L}{\mathsf{-}\mathsf{I}}_{\mathsf{N}})}$[35]p. 277
${\displaystyle \phi (1,0,0,0)}$		${\displaystyle {\mathsf{p}}_1({\mathrm{\Sigma }}_1^1{\mathsf{-}\mathsf{T}\mathsf{D}\mathsf{C}}_0)}$[20]: 7
${\displaystyle {\psi }_{{\mathrm{\Omega }}_1}({\mathrm{\Omega }}^{{\mathrm{\Omega }}^{\omega }})}$		${\displaystyle {\mathsf{R}\mathsf{C}\mathsf{A}}_0^{\ast }+{\mathrm{\Pi }}_1^1{\mathsf{-}\mathsf{C}\mathsf{A}}^{-}}$,[36]${\displaystyle {\mathsf{p}}_3({\mathsf{A}\mathsf{C}\mathsf{A}}_0)}$[20]: 7
${\displaystyle \vartheta ({\mathrm{\Omega }}^{\mathrm{\Omega }})}$	${\displaystyle \mathsf{T}\mathsf{I}\mathsf{D}}$,${\displaystyle {\mathsf{T}\mathsf{I}\mathsf{D}}_1}$[21]p. 171	${\displaystyle {\mathsf{p}}_1({\mathsf{p}}_3({\mathsf{A}\mathsf{C}\mathsf{A}}_0))}$[20]: 7		${\displaystyle \mathsf{F}\mathsf{I}\mathsf{T}}$[21]p. 171
${\displaystyle {\psi }_0({\epsilon }_{\mathrm{\Omega }+1})}$[3]	${\displaystyle {\mathsf{I}\mathsf{D}}_1}$	${\displaystyle \text{W-}\widetilde{\mathbf{E}\mathbf{\Omega }}}$[12]p. 8	${\displaystyle \mathsf{K}\mathsf{P}}$,[2]${\displaystyle \mathsf{K}\mathsf{P}\omega }$,${\displaystyle \mathrm{K}\mathrm{P}\mathrm{u}}$[15]p. 869	${\displaystyle {\mathsf{M}\mathsf{L}}_1\mathsf{V}}$	${\displaystyle \mathsf{C}\mathsf{Z}\mathsf{F}}$	${\displaystyle \mathsf{E}\mathsf{O}\mathsf{N}}$
${\displaystyle \psi ({\epsilon }_{\mathrm{\Omega }+{\epsilon }_0})}$		${\displaystyle \widetilde{\mathbf{E}\mathbf{\Omega }}}$[12]p. 31,${\displaystyle {\widetilde{\mathbf{E}\mathbf{I}\mathbf{D}}}_{\mathbf{1}}}$[12]p. 31,${\displaystyle \mathbf{A}\mathbf{C}\mathbf{A}+({\mathrm{\Pi }}_1^1\text{-CA}{)}^{-}}$[12]p. 31
${\displaystyle \psi ({\epsilon }_{\mathrm{\Omega }+\mathrm{\Omega }})}$		${\displaystyle ({\mathsf{I}\mathsf{D}}_1^2{)}_0+\mathsf{B}\mathsf{R}}$[37]
${\displaystyle \psi ({\epsilon }_{{\epsilon }_{\mathrm{\Omega }+1}})}$		${\displaystyle \mathbf{E}\mathbf{\Omega }}$[12]p. 33,${\displaystyle {\mathbf{E}\mathbf{I}\mathbf{D}}_{\mathbf{1}}}$[12]p. 33,${\displaystyle \mathbf{A}\mathbf{C}\mathbf{A}+({\mathrm{\Pi }}_1^1\text{-CA}{)}^{-}+({\mathrm{B}\mathrm{I}}_{\mathrm{P}\mathrm{R}}{)}^{-}}$[12]p. 33
${\displaystyle {\psi }_0({\mathrm{\Gamma }}_{\mathrm{\Omega }+1})}$[4]	${\displaystyle {\mathsf{U}\mathsf{(}\mathsf{I}\mathsf{D}}_1\mathsf{)}}$,[29]p. 26,${\displaystyle {\mathrm{\Sigma }}_1^1{\mathsf{-}\mathsf{D}\mathsf{C}}_0^{\bullet }+({\mathsf{S}\mathsf{U}\mathsf{B}}^{\bullet })}$[29]p. 26,${\displaystyle {\mathsf{A}\mathsf{T}\mathsf{R}}_0^{\bullet }}$[29]p. 26,${\displaystyle {\mathrm{\Sigma }}_1^1{\mathsf{-}\mathsf{A}\mathsf{C}}_0^{\bullet }+({\mathsf{S}\mathsf{U}\mathsf{B}}^{\bullet })}$[29]p. 26,${\displaystyle \mathcal{U}({\mathsf{I}\mathsf{D}}_1)}$[29]p. 26	${\displaystyle {\mathsf{F}\mathsf{P}}_0^{\bullet }}$[29]p. 26,${\displaystyle {\mathsf{A}\mathsf{T}\mathsf{R}}_0^{\bullet }}$[29]p. 26
	${\displaystyle \mathsf{A}\mathsf{u}\mathsf{t}\mathsf{(}\mathsf{U}\mathsf{(}\mathsf{I}\mathsf{D}\mathsf{)}\mathsf{)}}$
${\displaystyle {\psi }_0({\mathrm{\Omega }}_{\omega })}$	[4]p. 28	${\displaystyle {\mathsf{\Pi }}_1^1{\mathsf{-}\mathsf{C}\mathsf{A}}_0}$[4]p. 28,${\displaystyle {\mathsf{\Delta }}_2^1{\mathsf{-}\mathsf{C}\mathsf{A}}_0}$		${\displaystyle \mathsf{M}\mathsf{L}\mathsf{W}}$		${\displaystyle \mathsf{S}\mathsf{U}\mathsf{S}+(\mathsf{S}-{\mathsf{I}}_{\mathsf{N}})}$[38]p. 27
${\displaystyle {\psi }_0({\mathrm{\Omega }}_{\omega }{\omega }^{\omega })}$		${\displaystyle {\mathrm{\Pi }}_1^1{\mathsf{-}\mathsf{C}\mathsf{A}}_0+{\mathrm{\Pi }}_2^1\mathsf{-}\mathsf{I}\mathsf{N}\mathsf{D}}$[39]
${\displaystyle {\psi }_0({\mathrm{\Omega }}_{\omega }{\epsilon }_0)}$	${\displaystyle {\mathsf{W}\mathsf{-}\mathsf{I}\mathsf{D}}_{\omega }}$	${\displaystyle {\mathsf{\Pi }}_1^1\mathsf{-}\mathsf{C}\mathsf{A}}$[40]p. 14	${\displaystyle \mathsf{W}\mathsf{-}\mathsf{K}\mathsf{P}\mathsf{I}}$
${\displaystyle {\psi }_0({\mathrm{\Omega }}_{\omega }\mathrm{\Omega })}$		${\displaystyle {\mathrm{\Pi }}_1^1\mathsf{-}\mathsf{C}\mathsf{A}\mathsf{+}\mathsf{B}\mathsf{R}}$[41]
${\displaystyle {\psi }_0({\mathrm{\Omega }}_{\omega }^{\omega })}$		${\displaystyle {\mathrm{\Pi }}_1^1{\mathsf{-}\mathsf{C}\mathsf{A}}_0+{\mathrm{\Pi }}_2^1\mathsf{-}\mathsf{B}\mathsf{I}}$[39]
${\displaystyle {\psi }_0({\mathrm{\Omega }}_{\omega }^{{\omega }^{\omega }})}$		${\displaystyle {\mathrm{\Pi }}_1^1{\mathsf{-}\mathsf{C}\mathsf{A}}_0+{\mathrm{\Pi }}_2^1\mathsf{-}\mathsf{B}\mathsf{I}+{\mathrm{\Pi }}_3^1\mathsf{-}\mathsf{I}\mathsf{N}\mathsf{D}}$[39]
${\displaystyle {\psi }_0({\epsilon }_{{\mathrm{\Omega }}_{\omega }+1})}$[5]	${\displaystyle {\mathsf{I}\mathsf{D}}_{\omega }}$	${\displaystyle {\mathsf{\Pi }}_1^1\mathsf{-}\mathsf{C}\mathsf{A}\mathsf{+}\mathsf{B}\mathsf{I}}$	${\displaystyle \mathsf{K}\mathsf{P}\mathsf{I}}$
${\displaystyle {\psi }_0({\mathrm{\Omega }}_{{\omega }^{\omega }})}$		${\displaystyle {\mathsf{\Delta }}_2^1\mathsf{-}\mathsf{C}\mathsf{R}}$[4]p. 28				${\displaystyle \mathsf{S}\mathsf{U}\mathsf{S}+(\mathsf{N}-{\mathsf{I}}_{\mathsf{N}})}$[38]p. 27
${\displaystyle {\psi }_0({\mathrm{\Omega }}_{{\epsilon }_0})}$		${\displaystyle {\mathsf{\Delta }}_2^1\mathsf{-}\mathsf{C}\mathsf{A}}$[4]p. 28,${\displaystyle {\mathsf{\Sigma }}_2^1\mathsf{-}\mathsf{A}\mathsf{C}}$	${\displaystyle \mathsf{W}\mathsf{-}\mathsf{K}\mathsf{P}\mathsf{i}}$			${\displaystyle \mathsf{S}\mathsf{U}\mathsf{S}+(\mathrm{L}-{\mathsf{I}}_{\mathsf{N}})}$[38]p. 27
${\displaystyle {\psi }_0({\mathrm{\Omega }}_{\mathrm{\Omega }})}$	${\displaystyle \mathsf{A}\mathsf{u}\mathsf{t}\mathsf{(}\mathsf{I}\mathsf{D}\mathsf{)}}$[6]
${\displaystyle {\psi }_{{\mathrm{\Omega }}_1}({\epsilon }_{{\mathrm{\Omega }}_{\mathrm{\Omega }}+1})}$	${\displaystyle {\mathsf{I}\mathsf{D}}_{{\prec }^{\ast }}}$,${\displaystyle {\mathsf{B}\mathsf{I}\mathsf{D}}^{2\ast }}$,${\displaystyle {\mathsf{I}\mathsf{D}}^{2\ast }+\mathsf{B}\mathsf{I}}$[42]		${\displaystyle {\mathsf{K}\mathsf{P}\mathsf{l}}^{\ast }}$,${\displaystyle {\mathsf{K}\mathsf{P}\mathsf{l}}_{\mathrm{\Omega }}^r}$
${\displaystyle {\psi }_0({\mathrm{\Phi }}_1(0))}$		${\displaystyle {\mathrm{\Pi }}_1^1{\mathsf{-}\mathsf{T}\mathsf{R}}_0}$,${\displaystyle {\mathrm{\Pi }}_1^1{\mathsf{-}\mathsf{T}\mathsf{R}}_0+{\mathrm{\Delta }}_2^1{\mathsf{-}\mathsf{C}\mathsf{A}}_0}$,${\displaystyle {\mathrm{\Delta }}_2^1\mathsf{-}\mathsf{C}\mathsf{A}\mathsf{+}\mathsf{B}\mathsf{I}\mathsf{(}\mathsf{i}\mathsf{m}\mathsf{p}\mathsf{l}\mathsf{-}{\mathrm{\Sigma }}_2^1)}$,${\displaystyle {\mathrm{\Delta }}_2^1\mathsf{-}\mathsf{C}\mathsf{A}\mathsf{+}\mathsf{B}\mathsf{R}\mathsf{(}\mathsf{i}\mathsf{m}\mathsf{p}\mathsf{l}\mathsf{-}{\mathrm{\Sigma }}_2^1)}$,${\displaystyle {\mathbf{A}\mathbf{U}\mathbf{T}\mathbf{-}\mathbf{I}\mathbf{D}}_0^{pos}}$,${\displaystyle {\mathbf{A}\mathbf{U}\mathbf{T}\mathbf{-}\mathbf{I}\mathbf{D}}_0^{mon}}$[42]: 72	${\displaystyle {\mathsf{K}\mathsf{P}\mathsf{i}}^w+\mathsf{F}\mathsf{O}\mathsf{U}\mathsf{N}\mathsf{D}\mathsf{R}(\mathsf{i}\mathsf{m}\mathsf{p}\mathsf{l}\mathsf{-})\mathrm{\Sigma })}$,[42]: 72 ${\displaystyle {\mathsf{K}\mathsf{P}\mathsf{i}}^w+\mathsf{F}\mathsf{O}\mathsf{U}\mathsf{N}\mathsf{D}(\mathsf{i}\mathsf{m}\mathsf{p}\mathsf{l}\mathsf{-})\mathrm{\Sigma })}$,[42]: 72  ${\displaystyle {\mathbf{A}\mathbf{U}\mathbf{T}\mathbf{-}\mathbf{K}\mathbf{P}\mathbf{l}}^r}$,${\displaystyle {\mathbf{A}\mathbf{U}\mathbf{T}\mathbf{-}\mathbf{K}\mathbf{P}\mathbf{l}}^r+{\mathbf{K}\mathbf{P}\mathbf{i}}^r}$[42]: 72
${\displaystyle {\psi }_0({\mathrm{\Phi }}_1(0){\epsilon }_0)}$		${\displaystyle {\mathrm{\Pi }}_1^1\mathsf{-}\mathsf{T}\mathsf{R}}$,${\displaystyle {\mathbf{A}\mathbf{U}\mathbf{T}\mathbf{-}\mathbf{I}\mathbf{D}}^{pos}}$,${\displaystyle {\mathbf{A}\mathbf{U}\mathbf{T}\mathbf{-}\mathbf{I}\mathbf{D}}^{mon}}$[42]: 72	${\displaystyle {\mathbf{A}\mathbf{U}\mathbf{T}\mathbf{-}\mathbf{K}\mathbf{P}\mathbf{l}}^w}$[42]: 72
${\displaystyle {\psi }_0({\epsilon }_{{\mathrm{\Phi }}_1(0)+1})}$		${\displaystyle {\mathrm{\Pi }}_1^1\mathsf{-}\mathsf{T}\mathsf{R}+(\mathsf{B}\mathsf{I})}$,${\displaystyle {\mathbf{A}\mathbf{U}\mathbf{T}\mathbf{-}\mathbf{I}\mathbf{D}}_2^{pos}}$,${\displaystyle {\mathbf{A}\mathbf{U}\mathbf{T}\mathbf{-}\mathbf{I}\mathbf{D}}_2^{mon}}$[42]: 72	${\displaystyle \mathbf{A}\mathbf{U}\mathbf{T}\mathbf{-}\mathbf{K}\mathbf{P}\mathbf{l}}$[42]: 72
${\displaystyle {\psi }_0({\mathrm{\Phi }}_1({\epsilon }_0))}$		${\displaystyle {\mathrm{\Pi }}_1^1\mathsf{-}\mathsf{T}\mathsf{R}+{\mathrm{\Delta }}_2^1\mathsf{-}\mathsf{C}\mathsf{A}}$,${\displaystyle {\mathrm{\Pi }}_1^1\mathsf{-}\mathsf{T}\mathsf{R}+{\mathrm{\Sigma }}_2^1\mathsf{-}\mathsf{A}\mathsf{C}}$[42]: 72	${\displaystyle {\mathbf{A}\mathbf{U}\mathbf{T}\mathbf{-}\mathbf{K}\mathbf{P}\mathbf{l}}^w+{\mathbf{K}\mathbf{P}\mathbf{i}}^w}$[42]: 72
${\displaystyle {\psi }_0({\mathrm{\Phi }}_{\omega }(0))}$		${\displaystyle {\mathrm{\Delta }}_2^1{\mathsf{-}\mathsf{T}\mathsf{R}}_0}$,${\displaystyle {\mathrm{\Sigma }}_2^1{\mathsf{-}\mathsf{T}\mathsf{R}\mathsf{D}\mathsf{C}}_0}$,${\displaystyle {\mathrm{\Delta }}_2^1{\mathsf{-}\mathsf{C}\mathsf{A}}_0+({\mathrm{\Sigma }}_2^1\mathsf{-}\mathsf{B}\mathsf{I})}$[42]: 72	${\displaystyle {\mathbf{K}\mathbf{P}\mathbf{i}}^r+(\mathrm{\Sigma }\mathsf{-}\mathsf{F}\mathsf{O}\mathsf{U}\mathsf{N}\mathsf{D})}$,${\displaystyle {\mathbf{K}\mathbf{P}\mathbf{i}}^r+(\mathrm{\Sigma }\mathsf{-}\mathsf{R}\mathsf{E}\mathsf{C})}$[42]: 72
${\displaystyle {\psi }_0({\mathrm{\Phi }}_{{\epsilon }_0}(0))}$		${\displaystyle {\mathrm{\Delta }}_2^1\mathsf{-}\mathsf{T}\mathsf{R}}$,${\displaystyle {\mathrm{\Sigma }}_2^1\mathsf{-}\mathsf{T}\mathsf{R}\mathsf{D}\mathsf{C}}$,${\displaystyle {\mathrm{\Delta }}_2^1\mathsf{-}\mathsf{C}\mathsf{A}+({\mathrm{\Sigma }}_2^1\mathsf{-}\mathsf{B}\mathsf{I})}$[42]: 72	${\displaystyle {\mathbf{K}\mathbf{P}\mathbf{i}}^w+(\mathrm{\Sigma }\mathsf{-}\mathsf{F}\mathsf{O}\mathsf{U}\mathsf{N}\mathsf{D})}$,${\displaystyle {\mathbf{K}\mathbf{P}\mathbf{i}}^w+(\mathrm{\Sigma }\mathsf{-}\mathsf{R}\mathsf{E}\mathsf{C})}$[42]: 72
${\displaystyle \psi ({\epsilon }_{I+1})}$[7]		${\displaystyle {\mathsf{\Delta }}_2^1\mathsf{-}\mathsf{C}\mathsf{A}\mathsf{+}\mathsf{B}\mathsf{I}}$[4]p. 28,${\displaystyle {\mathsf{\Sigma }}_2^1\mathsf{-}\mathsf{A}\mathsf{C}\mathsf{+}\mathsf{B}\mathsf{I}}$	${\displaystyle \mathsf{K}\mathsf{P}\mathsf{i}}$		${\displaystyle \mathsf{C}\mathsf{Z}\mathsf{F}\mathsf{+}\mathsf{R}\mathsf{E}\mathsf{A}}$	${\displaystyle {\mathsf{T}}_0}$
${\displaystyle \psi ({\mathrm{\Omega }}_{I+\omega })}$				${\displaystyle {\mathsf{M}\mathsf{L}}_1\mathsf{W}}$[43]: 38
${\displaystyle \psi ({\mathrm{\Omega }}_L)}$[8]			${\displaystyle \mathsf{K}\mathsf{P}\mathsf{h}}$
${\displaystyle \psi ({\mathrm{\Omega }}_{L^{\ast }})}$[9]				${\displaystyle \mathsf{A}\mathsf{u}\mathsf{t}\mathsf{(}\mathsf{M}\mathsf{L}\mathsf{W}\mathsf{)}}$
${\displaystyle {\psi }_{\mathrm{\Omega }}({\chi }_{{\epsilon }_{M+1}}(0))}$[10]		${\displaystyle {\mathsf{\Delta }}_2^1\mathsf{-}\mathsf{C}\mathsf{A}\mathsf{+}\mathsf{B}\mathsf{I}\mathsf{+}\mathsf{(}\mathsf{M}\mathsf{)}}$[44]	${\displaystyle \mathsf{K}\mathsf{P}\mathsf{M}}$		${\displaystyle \mathsf{C}\mathsf{Z}\mathsf{F}\mathsf{M}}$
${\displaystyle \psi ({\mathrm{\Omega }}_{M+\omega })}$[11]			${\displaystyle {\mathsf{K}\mathsf{P}\mathsf{M}}^{+}}$[45]	${\displaystyle \mathsf{T}\mathsf{T}\mathsf{M}}$[45]
${\displaystyle {\mathrm{\Psi }}_{\mathrm{\Omega }}^0({\epsilon }_{K+1})}$[12]			${\displaystyle {\mathsf{K}\mathsf{P}\mathsf{+}\mathsf{\Pi }}_3-\mathsf{R}\mathsf{e}\mathsf{f}}$[46]
${\displaystyle {\mathrm{\Psi }}_{({\omega }^{+};P_0,ϵ,ϵ,0)}^{{\epsilon }_{\mathrm{\Xi }+1}}}$[13]			${\displaystyle {\mathsf{K}\mathsf{P}\mathsf{+}\mathsf{\Pi }}_{\omega }-\mathsf{R}\mathsf{e}\mathsf{f}}$[47]
${\displaystyle {\mathrm{\Psi }}_{({\omega }^{+};P_0,ϵ,ϵ,0)}^{{\epsilon }_{\mathrm{{\rm Y}}+1}}}$[14]			${\displaystyle \mathsf{S}\mathsf{t}\mathsf{a}\mathsf{b}\mathsf{i}\mathsf{l}\mathsf{i}\mathsf{t}\mathsf{y}}$[47]
${\displaystyle {\psi }_{{\omega }_1^{CK}}({\epsilon }_{{\mathbb{S}}^{+}+1})}$[48]			${\displaystyle \mathsf{K}\mathsf{P}\omega +{\mathrm{\Pi }}_1^1-\mathsf{R}\mathsf{e}\mathsf{f}}$,[48]${\displaystyle \mathsf{K}\mathsf{P}\omega +(M{\prec }_{{\mathrm{\Sigma }}_1}V)}$[49]
${\displaystyle {\psi }_{{\omega }_1^{CK}}({\epsilon }_{\mathbb{I}+1})}$[48]		${\displaystyle {\mathrm{\Sigma }}_3^1\mathsf{-}\mathsf{D}\mathsf{C}\mathsf{+}\mathsf{B}\mathsf{I}}$,${\displaystyle {\mathrm{\Sigma }}_3^1\mathsf{-}\mathsf{A}\mathsf{C}\mathsf{+}\mathsf{B}\mathsf{I}}$	${\displaystyle \mathsf{K}\mathsf{P}\omega +{\mathrm{\Pi }}_1-\mathsf{C}\mathsf{o}\mathsf{l}\mathsf{l}\mathsf{e}\mathsf{c}\mathsf{t}\mathsf{i}\mathsf{o}\mathsf{n}+(V=L)}$
${\displaystyle {\psi }_{{\omega }_1^{CK}}({\epsilon }_{{\mathbb{I}}_N+1})}$[50]		${\displaystyle {\mathrm{\Sigma }}_{N+2}^1\mathsf{-}\mathsf{D}\mathsf{C}\mathsf{+}\mathsf{B}\mathsf{I}}$,${\displaystyle {\mathrm{\Sigma }}_{N+2}^1\mathsf{-}\mathsf{A}\mathsf{C}\mathsf{+}\mathsf{B}\mathsf{I}}$	${\displaystyle \mathsf{K}\mathsf{P}\omega +{\mathrm{\Pi }}_N-\mathsf{C}\mathsf{o}\mathsf{l}\mathsf{l}\mathsf{e}\mathsf{c}\mathsf{t}\mathsf{i}\mathsf{o}\mathsf{n}+(V=L)}$
${\displaystyle {\psi }_{{\omega }_1^{CK}}({\mathbb{I}}_{\omega })}$[50]	[50]	${\displaystyle {\mathbf{Z}}_2}$,${\displaystyle {\mathrm{\Pi }}_{\mathrm{\infty }}^1-\mathsf{C}\mathsf{A}}$, Bar	${\displaystyle \mathsf{K}\mathsf{P}+{\mathrm{\Pi }}_{\omega }^{\text{set}}-\mathsf{S}\mathsf{e}\mathsf{p}\mathsf{a}\mathsf{r}\mathsf{a}\mathsf{t}\mathsf{i}\mathsf{o}\mathsf{n}}$	${\displaystyle \lambda 2}$[51]	${\displaystyle \mathsf{C}\mathsf{Z}\mathsf{F}\mathsf{+}\mathsf{S}\mathsf{e}\mathsf{p}}$[52]