DAAT · LEVEL 3 — MAGISTERIAL SYNTHESIS
Siman שס"ד
סימן שס"ד · דִּין מָבוֹי הַמְּפֻלָּשׁ וְעָשׂוּי כְּנָדָל
Recap & mnemonics for review
📑 Synthesis plan
- The central axiom of the siman
- The condensed key concepts
- Hierarchy of tikun — from weakest to strongest
- Decision tree
- Special cases (bent, nadal, street)
- Mnemonic פֶּתַח
- Pitfalls to avoid
- Practical cases
- Final synthesis table
- The practical commandments
1. The central axiom
Siman שס"ד in one sentence.
The more an alleyway opens to the outside, the stronger its tikun must be. A mefulash mavoy (open on both ends) is not saved by a simple lechi like the ordinary mavoy: it requires a tzuras hapesach (צוּרַת הַפֶּתַח) on one side — for that counts as a full mechitzah and strips away the "mefulash" status.
The more an alleyway opens to the outside, the stronger its tikun must be. A mefulash mavoy (open on both ends) is not saved by a simple lechi like the ordinary mavoy: it requires a tzuras hapesach (צוּרַת הַפֶּתַח) on one side — for that counts as a full mechitzah and strips away the "mefulash" status.
2. The condensed key concepts
| Concept | Definition | Application |
|---|---|---|
| מָבוֹי | Alleyway lined with chatzeros and houses | Mutar for carrying after tikun |
| מָבוֹי מְפֻלָּשׁ | Mavoy open on both ends | Requires more than a simple lechi |
| לֶחִי / קוֹרָה | Vertical post / horizontal beam | Tikun of a simple mavoy |
| צוּרַת הַפֶּתַח | Two posts + a crossbeam | Counts as a mechitzah; "closes" the mefulash side |
| דְּלָתוֹת | Doors fit to close at night | Only tikun for true reshus harabbim |
| נָדָל | Centipede: artery + grafted alleyways | Tzuras hapesach at each junction |
3. Hierarchy of tikun
Mavoy closed at one end (siman 363) → a simple lechi or korah suffices.
↓ more open
Mavoy hamefulash (both ends on reshus harabbim or karmelis) → tzuras hapesach on one side + lechi/korah on the other.
↓ more open
Street / true reshus harabbim → neither lechi nor tzuras hapesach suffices → real doors, fit to be closed at night.
4. Decision tree
Q1: Is the alleyway open at both ends (mefulash)?
↓ NO → ordinary mavoy, lechi/korah suffices (siman 363); YES ↓
Q2: Do both ends open to the street or to a karmelis?
↓ YES → tzuras hapesach on one side + lechi/korah on the other; one end opens to a non-eruv chatzer ↓
Q3: The side opens to a closed chatzer → lechi/korah suffices on both ends.
↓
→ For any eruv project → consult your Rav.
5. Special cases
| Configuration | Required tikun |
|---|---|
| Mavoy bent like ד (one bend) | Tzuras hapesach at the bend + lechi/korah at both ends (or the reverse) |
| Mavoy bent like ח (two bends) | Tzuras hapesach at both bends + lechi/korah at both ends |
| Mavoyot opening one into another | The inner mavoy is treated as open to the street, by chain |
| Mavoy shaped like נָדָל (centipede) | Tzuras hapesach at each small/large mavoy junction; lechi/korah at the opening to the street |
| Street (true reshus harabbim) | Doors fit to be closed at night; then the entirety becomes "one chatzer" |
6. Mnemonic פֶּתַח
פ — פִּלּוּשׁ: a mefulash mavoy, open on both ends, is not satisfied with a lechi.
ת — תְּמוּנַת הַפֶּתַח: the tzuras hapesach counts as a mechitzah — it closes a side and lifts the "mefulash" status.
ח — חָצֵר וְעִקּוּם: a side facing a closed chatzer → lechi suffices; a bend → treated as an open end.
7. Pitfalls to avoid
Pitfall 1: Believing that a lechi on both sides suffices for a mefulash alleyway. The mavoy hamefulash requires a tzuras hapesach on one side.
Pitfall 2: Thinking that the tzuras hapesach permits carrying on a real street. Miderabbanan, it does not suffice for true reshus harabbim — real doors are needed.
Pitfall 3: Forgetting the bend. A bent mavoy is treated as mefulash at its bend: the tzuras hapesach must be placed there, visible to inhabitants of both branches.
Pitfall 4: Confusing a chatzer included in the eruv with one not included. The status of the side open to a chatzer depends on this distinction (and on the chatzer's regular use).
8. Practical cases
| Situation | Analysis | Conduct |
|---|---|---|
| Alleyway closed at one end | Ordinary mavoy | Lechi or korah (siman 363) |
| Mefulash alleyway opening to the street | Mavoy hamefulash | Tzuras hapesach + lechi/korah |
| Alleyway opening to a closed chatzer | Side not "mefulash" | Lechi/korah on both ends |
| L- or S-shaped alleyway | Bent mavoy | Tzuras hapesach at the bend |
| Network of alleyways onto an artery | Nadal-shaped mavoy | Tzuras hapesach at each junction |
9. Final synthesis table
| Element | Detail |
|---|---|
| Topic of the siman | Mavoy hamefulash and the centipede-shaped mavoy |
| Number of seifim | 5 (Mechaber) — 9 in the Shulchan Aruch HaRav |
| Mishnah Berurah | 19 entries |
| Talmudic source | מסכת עירובין — sugya of the mavoy hamefulash |
| Golden rule | The more open the alleyway, the stronger its tikun: lechi → tzuras hapesach → doors |
| Practical decision | Exact measurement of openings and bends; consult your Rav for any eruv |
10. The practical commandments of Siman שס"ד
For daily conduct
- Mavoy hamefulash: tzuras hapesach on one side, lechi or korah on the other.
- The tzuras hapesach counts as a mechitzah: it strips away the "mefulash" status.
- Side opening to a closed chatzer: lechi or korah suffices on both ends.
- Bent mavoy: the tzuras hapesach is placed at the bend, visible from both branches.
- True street: only real doors (fit to be closed at night) make it mutar.
- For any eruv project — consult your Rav.
📚 Recap of the study path
You have studied Siman שס"ד in 3 levels:
You have studied Siman שס"ד in 3 levels:
- 🌱 Level 1 — Base: the 5 seifim, English translation, halachic concepts
- ⚡ Level 2 — Lamdan: talmudic sources, שיטות of the Rishonim, מחלוקות, נפקא מינות
- ✨ Level 3 — Synthesis: axiom, mnemonic, decision tree, practical commandments