Rule. The affix yaṅ undergoes luk when the suffix ac follows. By the word ca "and", it also undergoes luk "variously" (bahulam) even without that suffix. Bahulam means that the rule applies in some places and not in others.
The sūtra is short, and two words come from elsewhere by anuvṛtti. "Luk" comes from SK 1276 (ṇyakṣatriyārṣañito yūni luk aṇiñoḥ). "Bahulam" is drawn in by the ca from bahulaṃ chandasi, a rule of the Vedic section (SK 3400). Bhaṭṭoji's gloss takes aci as the suffix ac, a kṛt affix. It does not mean the pratyāhāra ac "any vowel". His commentators give the reason, association (sāhacarya): it stands beside yaṅ, which is a suffix too.
Two kinds of luk. Bhaṭṭoji names the kind that occurs without ac anaimittika, "unconditioned". Nothing that follows causes it. Being antaraṅga, it applies first. An antaraṅga operation is one that depends on less, or on what lies nearer the root; it takes effect before its rivals.
Bhaṭṭoji's commentators supply the other kind. Both call the luk before the suffix ac naimittika, "conditioned": the ac causes it. Both tie it to SK 2656: the guṇa the suffix ac would bring is barred, because the ac causes the deletion of the yaṅ. One of them, the Bālamanoramā, adds that this luk is therefore bahiraṅga, the opposite of antaraṅga. So there doubling comes first, and the luk of yaṅ after it.
Example (without ac). Bhaṭṭoji gives the order of steps. The root is bhū "to be".
bhū + yaṅ (the intensive affix of chapter 56)
→ this rule: luk of yaṅ, unconditioned, so antaraṅga, so first → bhū
→ the yaṅ is gone, but by pratyayalakṣaṇa (SK 262) the root still counts as ending in yaṅ
→ so doubling by sanyaṅoḥ (SK 2395) → bhū bhū
→ the operations on the abhyāsa (abhyāsakārya): shortening (SK 2180) → bhu bhū; b for bh (SK 2182) → bu bhū; guṇa of the abhyāsa by guṇo yaṅlukoḥ (SK 2630) → bobhū
→ the whole is a dhātu (SK 2304), so the lakāras come: laṭ
→ parasmaipada by śeṣāt kartari parasmaipadam (SK 2159): the ending tip → bobhū + ti
→ śap comes (SK 2167) and undergoes luk, because carkarītaṃ ca is read in the ad class (SK 2423) → bobhū + ti
→ the next sūtra gives bobhavīti and bobhoti.
Example (with ac). One of Bhaṭṭoji's commentators shows the other kind on the root lū.
lū + yaṅ → the luk is conditioned, so it waits; doubling comes first → lu lū + ya
→ guṇa of the abhyāsa (SK 2630) → lolūya
→ the kṛt suffix ac follows → this rule: luk of yaṅ → lolū + a
→ guṇa of ū before ac is due, but SK 2656 bars it → uvaṅ (SK 271) → loluva.
Without the luk, the same commentator gives lolūya. Without ac, he gives the pair bobhūyate (no luk, chapter 56) and bobhavīti (luk).
Applies when / blocked by. Does na lumatāṅgasya (SK 263) not stop the doubling? An affix removed by luk conditions no operation on the base. Bhaṭṭoji's commentators answer in two ways.
- One says doubling is an operation of the whole form ending in yaṅ. It is not an operation conditioned by the yaṅ. The dhātu name by SK 2304 is likewise not an operation on the base before the yaṅ. So SK 263 bars neither.
- The other reads the word sanyaṅoḥ in SK 2395 as a sixth case, "of what ends in san or yaṅ". Were it a seventh case, "when san or yaṅ follows", the elided yaṅ could not condition the doubling, and there would be none.
There is a second objection. Doubling by SK 2175 names "one vowel" (ekāc). The verse under SK 2246 says such rules do not hold in yaṅ-luk. Yet the root is doubled. Bhaṭṭoji's commentators answer that guṇo yaṅlukoḥ (SK 2630) prescribes guṇa for the abhyāsa in yaṅ-luk. That rule would be pointless if there were no doubling. So it is a jñāpaka: a sign in the wording of a sūtra that shows a further principle. Here the principle is that the prohibition in the verse is anitya, not invariable. Section B returns to this with han.
Parasmaipada only. Bhaṭṭoji says the stem takes parasmaipada by SK 2159, and not ātmanepada by anudāttaṅita ātmanepadam (SK 2157). Why not? Yaṅ is ṅit, marked with ṅ, and SK 2157 gives ātmanepada after a ṅit. But being ṅit is common to suffixes and non-suffixes. Bhaṭṭoji's commentators give citraṅ as a non-suffix with the marker ṅ. Pratyayalakṣaṇa holds only where a property exclusive (asādhāraṇa) to suffixes is relied upon. So it does not carry the ṅ of the deleted yaṅ.
Bhaṭṭoji gives a parallel. In sudṛṣatprāsādaḥ "[a palace] with fine stones", the lengthening of SK 425 does not take place. Bhaṭṭoji's commentators explain: the ending as that was deleted occurs both as a suffix and as a non-suffix. So the stem does not count as ending in as by pratyayalakṣaṇa.
What of roots that are themselves anudātta-marked or ṅit, such as spardh and śīṅ? Anudātta is the low pitch-accent. A root whose marker vowel is anudātta takes ātmanepada by SK 2157. Bhaṭṭoji says they too take no ātmanepada in yaṅ-luk. SK 2157 cites them by their marker (anubandha). The paribhāṣā śtipā śapā… excludes such a citation in yaṅ-luk. A paribhāṣā is a rule about how other rules are read. This one is the verse of SK 2246. One of Bhaṭṭoji's commentators says why Bhaṭṭoji does not use this second answer for bhū as well. Bhū is not cited with a marker. The ṅ of yaṅ belongs to the suffix, not to the whole form.
The vikaraṇa. By the same paribhāṣā, Bhaṭṭoji says, śyan and the other class-signs (vikaraṇa) do not come. They are taught by citing a class (gaṇa). Only śap comes. One of his commentators adds that śap comes because its rule, SK 2167, lies outside the prohibition. Then śap undergoes luk. The reason is that the line carkarītaṃ ca is read in the ad class. One of Bhaṭṭoji's commentators names the rule: adiprabhṛtibhyaḥ śapaḥ (SK 2423).
Watch out. The luk this chapter conjugates is the unconditioned one. It comes before doubling, not after. Do not confuse it with the conditioned luk before ac, which comes after doubling and which SK 2656 concerns. Some carried the word chandasi "in the Veda" into this sūtra as well, as if yaṅ-luk were Vedic only. One of Bhaṭṭoji's commentators refutes them; the other says that even on their view yaṅ-luk is sometimes used in ordinary speech. Bhaṭṭoji's own proof of that comes under SK 2651.
Let there be luk of yaṅ when the suffix (pratyaya) ac follows [— 'luk' carried forward (anuvṛtti) from SK 1276; 'ac' here is the suffix, not the pratyāhāra]. By the ca, let there variously (bahulam) be luk even without that [suffix — 'bahulam' drawn in from bahulaṃ chandasi, SK 3400]. This [luk, the one that occurs without the suffix ac,] is unconditioned (anaimittika); being antaraṅga, it takes place first. After that, doubling [by sanyaṅoḥ, SK 2395], because [the root] ends in yaṅ by pratyayalakṣaṇa [i.e. by pratyayalope pratyayalakṣaṇam, SK 262, although the yaṅ has been elided]. [Then] the operations on the abhyāsa (abhyāsakārya). Because [the whole] is a dhātu [by sanādyantā dhātavaḥ, SK 2304], laṭ and the other lakāras [are added]. Parasmaipada [comes] by śeṣāt kartari parasmaipadam (SK 2159). But not [ātmanepada] by anudāttaṅita ātmanepadam (SK 2157), because being ṅit is common to suffixes and non-suffixes, and so pratyayalakṣaṇa does not operate. For that [pratyayalakṣaṇa] holds only where a form exclusive (asādhāraṇa) to a suffix is relied upon. For this very reason, in sudṛṣatprāsādaḥ the lengthening by atvasantasya cādhātoḥ (SK 425) does not take place. Even those that are anudātta-it or ṅit, such as spardha and śīṅ — from them too [ātmanepada does] not [come in yaṅluk], because anudāttaṅita… (SK 2157) is a citation by anubandha, and for that [kind of citation] there is the prohibition [by the paribhāṣā] 'śtipā śapā…'. For this very reason śyan and the other [vikaraṇas] do not [come], because [they are taught] by citation of a gaṇa; only śap [comes]. Since 'carkarītaṃ ca' is read in the adādi [class], [there is] luk of śap.
- commentary TB on the sūtra itself (sk.2650.t1, opening; re-filed from the tail of sk.2649.t1 on 2026-10-05; NSP p. 439): by association (sāhacarya) with yaṅ, 'aci' denotes the suffix ac, not the pratyāhāra. 'luk' is carried forward (anuvartate) from ṇyakṣatriyārṣa… [SK 1276]; by ca, 'bahulam' is drawn in (anukṛṣyate) from bahulaṃ chandasi [SK 3400]. Some draw in 'chandasi' as well, but even on their view yaṅluk sometimes occurs in the spoken language (bhāṣā), on the indication (jñāpaka) of the irregular Vedic form bobhūtu, which is made restrictive because the guṇa-prohibition by bhūsuvoḥ was already established; this, TB says, will become clear in the mūla itself (SK 2651). Followed: the anuvṛtti brackets and 'the suffix, not the pratyāhāra'.
- commentary BM (absent from our source.json; read in Wikisource uttara-2/0135–0136) gives the same three points: aci is the suffix by association with yaṅ, luk is carried forward from ṇyakṣatriyārṣa…, and bahula is drawn in by ca. 'Without that' means 'even where there is no suffix ac'. So from lū with yaṅ and ac, lolūya [without luk] and loluva [with luk]; without ac, the optional luk gives bobhūyate and bobhavīti. Followed: '[even without that suffix]'.
- commentary BM (WS uttara-2/0135) on 'anaimittiko 'yam': the yaṅluk found elsewhere than before ac, as in bobhavīti, is unconditioned. So, being antaraṅga, it applies before doubling, even though doubling is the later (para) rule; Bhaṭṭoji is describing how things actually stand. The yaṅluk taught before the suffix ac is conditioned (naimittika) and therefore bahiraṅga. There doubling comes first, being para and nitya, and then the luk of yaṅ; the guṇa that the suffix ac would bring is barred by na dhātulopa ārdhadhātuke [SK 2656], because ac causes the deletion of yaṅ. Followed: 'This [luk, the one that occurs without the suffix ac,]'.
- commentary TB (sk.2650.t1): the yaṅluk taught before the suffix ac is conditioned (naimittika) by it, and that is how the prohibition na dhātulopa… [SK 2656] works in loluvaḥ and popuvaḥ. Followed: the contrast in 'This [luk, the one that occurs without the suffix ac,]'.
- commentary TB (sk.2650.t1) on 'yaṅantatvāt': in sanyaṅoḥ [SK 2395] the case ending is the sixth (ṣaṣṭhī), not the seventh. Were it the seventh, the yaṅ having been elided by luk, pratyayalakṣaṇa would not operate [by na lumatāṅgasya] and there would be no doubling. TB rejects the defence of the seventh-case view (that na lumatā… bars only operations taught in the aṅga section). Its ground is the settled view that na lumatā… covers everything, aṅga or not, prescribed for what precedes a following suffix; otherwise n would not be deleted in rājapuruṣaḥ. TB adds that the doubling by ekācaḥ… would be barred by śtipā śapā…, but it still takes place. guṇo yaṅlukoḥ and rugrikau ca luki prescribe operations on the abhyāsa, and so they show that the prohibition does not apply. Followed: '[the root] ends in yaṅ by pratyayalakṣaṇa'.
- commentary BM (WS uttara-2/0135) on 'tataḥ': 'after the luk of yaṅ'. na lumatāṅgasya [SK 263] bars only aṅga operations conditioned by the elided suffix. Doubling is an operation of the yaṅanta, not one conditioned by yaṅ. The dhātu designation (by sanādyantāḥ) belongs to the yaṅanta and is not an aṅga operation before yaṅ, so na lumatā… does not bar it. 'abhyāsakāryam' means guṇa and the like. BM also cites the same jñāpaka (guṇo yaṅlukoḥ) against the śtipā śapā… prohibition of doubling. Followed: the bracketed rule references.
- commentary TB (sk.2650.t1) on 'pratyayāpratyaya…': ṅit is found in suffixes (ṛter īyaṅ, etc.) and also in non-suffixes (citraṅ, etc.). So ātmanepada, an operation due to the ṅit of yaṅ, cannot be suspected here by pratyayalakṣaṇa. Bhaṭṭoji does not give here the other answer, 'ṅita ity anubandhanirdeśāt'. The reason is that roots such as bhū are not, like śīṅ, cited with an anubandha: the ṅ of yaṅ is the suffix's anubandha, not the whole's, so the yaṅanta is not cited with an anubandha either. Followed.
- commentary BM (WS uttara-2/0136) on 'pratyayāpratyaya…': pratyayalakṣaṇa operates only where an operation relies on a property found in suffixes alone, as when the elided sup makes rājan a pada in rājā; ṅit is found in non-suffixes such as citraṅ as well. Followed.
- commentary TB (sk.2650.t1) on sudṛṣat-: a bahuvrīhi, 'in which there are fine stones'; the word dṛṣad there ends in jas. No lengthening, because 'as' occurs both as suffix and as non-suffix, so no form exclusive to a suffix is relied upon and there is no as-finality by pratyayalakṣaṇa. Recorded; the English already says this.
- commentary BM (WS uttara-2/0136) on sudṛṣat-: there is no lengthening, because 'as' occurs both as suffix and as non-suffix, so there is no as-finality by pratyayalakṣaṇa. na lumatā… cannot be the reason, because the lengthening belongs to the as-final stem and is not an aṅga operation before jas. Recorded; the English already says this.
- commentary TB (sk.2650.t1) on 'tebhyo 'pi': that is, from those that are anudātta-it or ṅit without any pratyayalakṣaṇa. On 'adādau pāṭhāt': the sense is luk of śap after a yaṅluganta by adiprabhṛtibhyaḥ śapaḥ [SK 2423]. Followed: 'from them too [ātmanepada does] not [come in yaṅluk]'.
- commentary BM (WS uttara-2/0136) on 'ata eva': because of the śtipā śapā prohibition, the vikaraṇas taught by gaṇa (divādibhyaḥ śyan, rudhādibhyaḥ śnam, etc.) do not come; śap comes because kartari śap is outside the scope of that prohibition. Followed: '[vikaraṇas]'.
- textual The cross-reference after 'śeṣāt kartari' is SK 2149 in ours; the print has '2159' (NSP p. 439, scan page-0449, read), as does Wikisource. SK 2149 is yathāsve yathāyatham; śeṣāt kartari parasmaipadam is SK 2159. The English gives SK 2159. Our '[(paribhāṣā - ) śtipā śapā...]' is an editorial bracket and ellipsis; the print has '(pa) śtipā śapeti', and the words agree.
- textual No BM in our source.json for any unit of this prakaraṇa (sk2650–sk2656). Wikisource (uttara-2/0135–0153) has the full BM on the yaṅluganta-prakriyā, and it was read as the BM input throughout.