Symbol Reference: { x | ๐›— } / ฮบ — Class Comprehension Binder ({ x | ๐›— }, AST Constructor: CpKappa)

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Formula Display:
Proof Trees:

{ x | ๐›— } / ฮบ \(\{ x \mid \varphi \} \;/\; \kappa\) — Class Comprehension Binder ({ x | ๐›— }, AST Constructor: CpKappa)

The primitive class comprehension binder { x | ๐›— } (also denoted ฮบ) forms the class of all sets x : Class satisfying syntactic formula ๐›— : Fm. All three tokens {, |, and } in a comprehension expression resolve to this single binder symbol.

Field Mathematical & Kernel Specification (MKTD1 / MKTD2)
Symbol
{ x | ๐›— } / ฮบ
\(\{ x \mid \varphi \} \;/\; \kappa\)
Category Binder (Class-Forming Variable-Binding Functional Symbol)
SML AST Constructor HC (CpKappa of 'Class_Truth_FUNEX) [in datatype Class_p, typetheory.ML:554]
Constructor Arguments 1. Bound variable x : Variable (default type Class, never Set); 2. Formula matrix ๐›— : Fm (= Bool.Expression)
Metatype / Signature (Variable ร— Fm) โ†’ Class.Expression | Semantically: (Class โ†’ Bool) โ†’ Class
Binder Status YES โ€” Variable-Binding Class-Forming Functional Symbol (Binder). All three tokens '{', '|', and '}' in { x | ๐›— } link to this single symbol page.
Defining Kernel Entries (ML Labels) Inference Rule RulClassComprehension (3.01): Class comprehension (#RulClassComprehension / #label-class-comprehension)
LaTeX Form \{ x \mid \varphi \} \;/\; \kappa
How to Understand It

Kernel AST & Logical Specification of Class Comprehension:

  • SML AST Constructor (in ClassTerm / Class_p, typetheory.ML:554): HC (CpKappa of 'Class_Truth_FUNEX) where 'Class_Truth_FUNEX = Fm_LBound_id (LBound_id (LVariable_id vx, phi)).
  • Constructor Arguments (Arity 1 higher-order binder / 2 syntactic components):
    1. Bound variable x : Variable (ranging over default object type Class; never Set),
    2. Comprehension matrix / formula body ๐›— : Fm (= Bool.Expression).
  • Metatype / Signature: (Variable ร— Fm) โ†’ Class.Expression (or higher-order binder signature (Class โ†’ Bool) โ†’ Class).
  • Symbol Classification: Binder (variable-binding class-forming functional symbol). Clicking {, |, or } in {x | ๐›—} always navigates to this single symbol page.
  • Defining Axiom & Rule: Governed by RulClassComprehension (3.01) and AxmMetaClassComprehension (4.06), printed in full below.
Canonical Law / Usage โˆ€(k:Class.Expression)โˆ€(x:Name)โˆ€(๐›—:Fm)(FFI(k,โ€นxโ€บ,๐›—) โ†’ ((โŸฆkโŸง โˆˆ {โฆƒxโฆ„|โŸฆ๐›—โŸง}) โŸท ((โŸฆkโŸง set) โˆง (let โ€นxโ€บ = โŸฆkโŸง in โŸฆ๐›—โŸง))))
Related Symbols & Kernel Entries

Defining Axioms, Rules & Formal Definitions (Rendered Directly from Kernel Entries)

Generated without code duplication by invoking render_entry_row_base "../manual.html" on the corresponding kernel Entry records.

# Formal Entity Specification
3.01
Title Class comprehension #RulClassComprehension #label-class-comprehension
Classification Inference Rule
Formula
0\(\href{../symbols/delimiters-brackets.html}{(} \href{../symbols/delimiters-brackets.html}{(} \href{../symbols/binder-brackets.html}{\{\!\lvert } \href{../symbols/variables.html}{x} \href{../symbols/binder-brackets.html}{\rvert\!\}} \href{../symbols/in-pred.html}{\in} \href{../symbols/class-comprehension.html}{\{} \href{../symbols/binder-brackets.html}{\{\!\lvert } \href{../symbols/variables.html}{x} \href{../symbols/binder-brackets.html}{\rvert\!\}} \href{../symbols/class-comprehension.html}{ \mid } \href{../symbols/antiquotation.html}{[\![ } \href{../symbols/formula-metavariables.html}{\boldsymbol{\varphi}} \href{../symbols/antiquotation.html}{ ]\!]} \href{../symbols/class-comprehension.html}{\}} \href{../symbols/delimiters-brackets.html}{)} \href{../symbols/iff-conn.html}{\longleftrightarrow} \href{../symbols/delimiters-brackets.html}{(} \href{../symbols/delimiters-brackets.html}{(} \href{../symbols/binder-brackets.html}{\{\!\lvert } \href{../symbols/variables.html}{x} \href{../symbols/binder-brackets.html}{\rvert\!\}} \href{../symbols/set-pred.html}{\mathsf{set}} \href{../symbols/delimiters-brackets.html}{)} \href{../symbols/and-conn.html}{\land} \href{../symbols/antiquotation.html}{[\![ } \href{../symbols/formula-metavariables.html}{\boldsymbol{\varphi}} \href{../symbols/antiquotation.html}{ ]\!]} \href{../symbols/delimiters-brackets.html}{)} \href{../symbols/delimiters-brackets.html}{)} \)
SML Kernel AST PComprAx_prf
Scheme of Types 0(([โฆƒ[x@Variable.Expression]โฆ„@Class.Expression]โˆˆ{[โฆƒ[x@Variable.Expression]โฆ„@Class.Expression]|โŸฆ[๐›—@Fm.Expression]โŸง})โŸท(([โฆƒ[x@Variable.Expression]โฆ„@Class.Expression] set)โˆงโŸฆ[๐›—@Fm.Expression]โŸง))
Judgements
1\(\href{../symbols/image-op.html}{[} \href{../symbols/delimiters-brackets.html}{(} \href{../symbols/variables.html}{x} \href{../symbols/typing-colon.html}{:} \href{../symbols/name-sort.html}{\mathsf{Name}} \href{../symbols/delimiters-brackets.html}{)} \href{../symbols/comma-delim.html}{,} \href{../symbols/delimiters-brackets.html}{(} \href{../symbols/formula-metavariables.html}{\boldsymbol{\varphi}} \href{../symbols/typing-colon.html}{:} \href{../symbols/fm-sort.html}{\mathsf{Fm}} \href{../symbols/delimiters-brackets.html}{)} \href{../symbols/image-op.html}{]} \)
Side Condition
1\(\href{../symbols/top-const.html}{\top} \)
Verification Primitive / Derived Rule (Kernel) · Standalone Entry (RulClassComprehension) → · (3.01) · #RulClassComprehension