NeoCEG DSL Grammar Specification v1.0

Status: Finalized (2026-02-08) Language: English (primary) / 日本語 (説明)

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Overview / 概要

This document defines the formal grammar for the NeoCEG DSL (Domain-Specific Language) used to describe cause-effect graphs.

本ドキュメントは、NeoCEG DSL（原因結果グラフ記述言語）の正式文法を定義します。

Key Features / 主要特徴

• Human-readable syntax / 人間可読な構文
• Unicode support for node labels (Japanese, etc.) / ノードラベルのUnicode対応（日本語等）
• English-only keywords / キーワードは英語のみ
• Optional layout information / レイアウト情報はオプション

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EBNF Grammar / EBNF文法

(* NeoCEG DSL Grammar v1.0 *)

(* ============================================================================= *)
(* Top-level structure / 最上位構造 *)
(* ============================================================================= *)

program         = { statement } ;

statement       = comment
                | node_definition
                | constraint_stmt
                | layout_stmt ;

comment         = "#" text newline ;

(* ============================================================================= *)
(* Node definitions / ノード定義 *)
(* ============================================================================= *)

(* Cause node: identifier : "label" [unobservable] *)
(* Effect/Intermediate node: identifier := expression *)
node_definition = identifier ( cause_def | effect_def ) ;

cause_def       = ":" string [ observable_flag ] ;
effect_def      = ":=" expression ;

observable_flag = "[unobservable]" | "[observable]" ;  (* [observable] accepted for backward compatibility *)

(* ============================================================================= *)
(* Logical expressions / 論理式 *)
(* ============================================================================= *)

expression      = or_expr ;

or_expr         = and_expr { "OR" and_expr } ;

and_expr        = unary_expr { "AND" unary_expr } ;

unary_expr      = [ "NOT" ] primary_expr ;

primary_expr    = identifier
                | "(" expression ")" ;

(* ============================================================================= *)
(* Constraints / 制約 *)
(* ============================================================================= *)

constraint_stmt = symmetric_constraint
                | directional_constraint ;

(* Symmetric constraints: ONE, EXCL, INCL *)
symmetric_constraint = ( "ONE" | "EXCL" | "INCL" )
                       "(" member_list ")" ;

(* Directional constraints: REQ, MASK *)
(* REQ: NOT on source or targets, but not both simultaneously *)
(* MASK: NOT on trigger only, targets always positive *)
req_constraint  = "REQ" "(" constraint_member "->" member_list ")" ;
mask_constraint = "MASK" "(" constraint_member "->" identifier_list ")" ;
directional_constraint = req_constraint | mask_constraint ;

identifier_list = identifier { "," identifier } ;

member_list     = constraint_member { "," constraint_member } ;

constraint_member = [ "NOT" ] identifier ;

(* ============================================================================= *)
(* Layout section (optional) / レイアウトセクション（オプション） *)
(* ============================================================================= *)

layout_stmt     = "@layout" "{" { layout_entry } "}" ;

layout_entry    = identifier ":" "(" number "," number [ "," number ] ")" ;
                  (* x, y, optional width / x座標, y座標, 省略可能な幅 *)

(* ============================================================================= *)
(* Lexical elements / 字句要素 *)
(* ============================================================================= *)

identifier      = ( letter | unicode_letter ) { letter | digit | "_" | unicode_letter } ;

string          = '"' { string_char | escape_sequence } '"' ;

string_char     = (* any character except " and \ *) ;

escape_sequence = "\" ( "n" | '"' | "\" ) ;

number          = [ "-" ] digit { digit } ;

letter          = "a" - "z" | "A" - "Z" ;

digit           = "0" - "9" ;

unicode_letter  = (* Unicode letters: Hiragana, Katakana, Kanji, etc. *)
                  (* Ranges: U+3040-U+309F, U+30A0-U+30FF, U+4E00-U+9FFF *) ;

text            = (* any character until end of line *) ;

newline         = "\n" | "\r\n" ;

---

Semantic Rules / 意味規則

Node Roles / ノードの役割

Node roles are derived from graph structure, not explicitly specified:

ノードの役割はグラフ構造から自動判定され、明示的に指定しません：

Role / 役割	Definition / 定義	DSL Syntax / DSL構文
Cause / 原因	No incoming edges (in-degree = 0) / 入力辺なし	name: "label"
Effect / 結果	No outgoing edges (out-degree = 0) / 出力辺なし	name := expression
Intermediate / 中間	Has both incoming and outgoing edges / 入出力辺あり	name := expression

Keywords / キーワード

All keywords are case-insensitive but conventionally written in UPPERCASE.

キーワードは大文字小文字を区別しないが、慣例的に大文字で記述します。

Keyword / キーワード	Purpose / 用途
AND	Logical conjunction / 論理積
OR	Logical disjunction / 論理和
NOT	Logical negation / 否定
ONE	Exactly-one constraint / 排他的選択制約
EXCL	Exclusive constraint / 排他制約
INCL	Inclusive constraint / 包含制約
REQ	Requires constraint / 要求制約
MASK	Masking constraint / マスク制約

Operator Precedence / 演算子優先順位

Priority / 優先度	Operator / 演算子	Associativity / 結合性
1 (highest)	NOT	Right / 右結合
2	AND	Left / 左結合
3 (lowest)	OR	Left / 左結合

Observable Flag / 観測可能フラグ

• Default: ON for all nodes (all nodes are observable by default)
• デフォルト: すべてのノードでON（デフォルトで観測可能）
• [unobservable] marks a node as non-observable / [unobservable] で非観測可能を指定
• [observable] is accepted for backward compatibility (equivalent to default) / [observable] は後方互換のため受け入れる（デフォルトと同等）
• Can be toggled in the UI or specified in DSL / UIでトグル可能、またはDSLで指定可能

---

Example / 使用例

Basic Example / 基本例

# Login feature test design
# ログイン機能のテスト設計

# Causes (inputs)
valid_user_id: "Valid user ID entered"
password_match: "Password matches"
sso_enabled: "SSO is enabled"

# Intermediate nodes
auth_success := valid_user_id AND password_match
sso_auth := sso_enabled AND valid_user_id

# Effects (outputs)
login_result := auth_success OR sso_auth
error_display := NOT auth_success AND NOT sso_auth

# Constraints
ONE(auth_success, sso_auth)
REQ(sso_auth -> sso_enabled)

With Layout / レイアウト付き

# Same as above...

# Layout coordinates (optional, width is optional third value)
@layout {
  valid_user_id: (100, 100)
  password_match: (100, 200)
  sso_enabled: (100, 300)
  auth_success: (300, 150, 200)
  sso_auth: (300, 300)
  login_result: (500, 200)
  error_display: (500, 300, 250)
}

Japanese Labels / 日本語ラベル

# 日本語ノード名の例

# 原因（入力）
ユーザーID正常: "有効なユーザーIDが入力された"
パスワード一致: "パスワードが一致する"

# 結果（出力）
認証成功 := ユーザーID正常 AND パスワード一致
エラー表示 := NOT 認証成功

# 制約
EXCL(認証成功, エラー表示)

---

Constraints Semantics / 制約の意味

ONE - Exactly One / 排他的選択制約

Exactly one of the members must be true. メンバーのうちちょうど1つが真でなければならない。

ONE(A, B, C)

EXCL - Exclusive / 排他制約

At most one of the members can be true (zero is allowed). メンバーのうち最大1つが真（0個も可）。

EXCL(A, B, C)

INCL - Inclusive / 包含制約

At least one of the members must be true. メンバーのうち少なくとも1つが真でなければならない。

INCL(A, B, C)

REQ - Requires / 要求制約

If source is satisfied, then all targets must satisfy their conditions. sourceが成立するなら、すべてのtargetがその条件を満たさなければならない。

NOT is allowed on the source side or target side, but not both simultaneously. NOTはソース側またはターゲット側のいずれか一方のみ許可。両側同時のNOTは禁止。

Why both-sides-NOT is prohibited / 両側NOTを禁止する理由: REQ(NOT A -> NOT B) appears to mean "if A=F then B=F", but the double negation makes the intent ambiguous and error-prone. This is explicitly prohibited to prevent misunderstanding. REQ(NOT A -> NOT B) は「A=Fならば B=F」という意味に見えるが、二重否定は意図が曖昧でエラーを招きやすい。 誤解防止のため明示的に禁止する。

• REQ(A -> B, C) — If A=T then B=T and C=T
• REQ(NOT A -> B) — If A=F then B=T
• REQ(A -> NOT B) — If A=T then B=F

REQ(A -> B, C)        # If A=T then B and C must be T
REQ(NOT A -> B)       # If A=F then B must be T
REQ(A -> NOT B)       # If A=T then B must be F

MASK - Masking / マスク制約

If trigger is true, then all targets become don't-care (M). triggerが真なら、すべてのtargetがdon't-care（M）になる。

Note / 注: NOT is allowed on trigger (left of ->) only. NOT is prohibited on targets (right of ->). NOTはトリガー（->の左側）のみ許可。ターゲット（->の右側）のNOTは禁止。

Why target NOT is prohibited / ターゲットNOTを禁止する理由: The M (Don't Care) value is symmetric under negation — NOT M = M. Therefore, MASK(A -> NOT B) would have the same effect as MASK(A -> B), making target NOT meaningless. M値は否定に対して対称（NOT M = M）であるため、MASK(A -> NOT B) は MASK(A -> B) と同じ効果になり、ターゲットNOTは無意味。

REQ vs MASK asymmetry in NOT handling / REQとMASKのNOT処理の非対称性: This contrasts with REQ, where target NOT IS meaningful because REQ sets T/F values: これはREQと対照的で、REQはT/F値を設定するためターゲットNOTは意味がある： - REQ(A -> B): A=T → B=T - REQ(A -> NOT B): A=T → B=F (different result / 異なる結果) - MASK(A -> B): A=T → B=M - MASK(A -> NOT B): A=T → B=M (same result — NOT M = M / 同じ結果)

MASK(A -> B, C)       # If A=T then B=M and C=M
MASK(NOT A -> B, C)   # If A=F then B=M and C=M

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Compatibility / 互換性

Not Compatible with CEGTest 1.6 CSV / CEGTest 1.6 CSVとの非互換性

This DSL format is NOT compatible with CEGTest 1.6's CSV format.

このDSL形式はCEGTest 1.6のCSV形式と互換性がありません。

Design Decision: Prioritize human-readability and AI tool integration over legacy compatibility.

設計判断: レガシー互換性よりも人間可読性とAIツール連携を優先。

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Document History / ドキュメント履歴

Date / 日付	Version / バージョン	Changes / 変更内容
2026-02-08	1.0	Initial finalized version / 初版確定版
2026-03-01	1.1	Invert observable flag: [unobservable] replaces [observable] (backward compat kept) / observable反転：[unobservable]に変更（[observable]は後方互換維持）
2026-03-04	1.2	Add optional width to layout entry: (x, y, width) — backward compatible / レイアウトエントリに省略可能な幅を追加：(x, y, width) — 後方互換