Conflicting Sources on புணர்ச்சி and a Mislabelled வேற்றுமை
The night before the exam a candidate practises புணர்ச்சி. Her four items are: (1) மரம் + வேர்; (2) கல் + தூண்; (3) பூ + கொடி; (4) நிலா + ஒளி. One website gives மரம்வேர் for item (1); her printed guidebook gives மரவேர். For item (4) she writes நிலாஒளி. In the same exercise a வேற்றுமை question asks her to name the case of மரத்தால் and மரத்தை. She labels both 'ஐ வேற்றுமை', because both words end in a letter she associates with the accusative. She has 40 minutes and three sources that disagree, and she wants a rule she can apply under exam conditions rather than a memorised list.
1. Resolve the four புணர்ச்சி items, showing the rule that governs each rather than only the final form.
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(1) மரம் + வேர் → மரவேர். The final ம் of the first word drops before the வ of the second; the website's மரம்வேர் keeps a consonant the rule removes, so the guidebook is right. (2) கல் + தூண் → கற்றூண். Here the final ல் does not simply drop: it changes to ற், and the following த் doubles. The doubling is the visible signal that a rule has applied. (3) பூ + கொடி → பூங்கொடி. A linking ங் is inserted before the வல்லினம் கொ; without it the words collide. (4) நிலா + ஒளி → நிலவொளி. The final ஆ becomes the glide வ before the initial vowel ஒ, so the two vowels do not meet directly - hence நிலாஒளி is wrong. The general lesson: identify the final sound of word one and the initial sound of word two, then ask whether the rule is elision, assimilation with doubling, or insertion of a linking letter.
2. Show how to identify the வேற்றுமை of மரத்தால் and மரத்தை reliably, and explain why the ending letters alone mislead.
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The surface letters cannot be trusted, because part of what she sees is sandhi rather than a case marker. The method is substitution: replace the noun with a simple one whose case endings are unambiguous, and see which marker survives. மரத்தால் becomes அவனால் - the marker is ஆல், the instrument or agent, which is the third வேற்றுமை. மரத்தை becomes அவனை - the marker is ஐ, the object of the action, which is the second வேற்றுமை. The த் in மரத்தால் belongs to the stem after sandhi, not to the case. A second check is functional: ask what role the word plays in the sentence. If it answers 'by means of what?' or 'by whom?', it is ஆல். If it answers 'whom/what does the action fall on?', it is ஐ. Both tests together are much safer than pattern-matching endings.
3. When a website and a printed guide disagree, what decision procedure should she use in the exam hall, and what should she do with the disputed form during revision?
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In the hall she needs a tie-breaker, not a debate. Three checks, in order. First, does the joined form exist as a word she has actually met in the textbook? Textbook forms are the safest authority because the paper is set from the textbook. Second, does the form obey the sound rule she can state aloud - elision, doubling, or linking letter? A form that requires no rule, like மரம்வேர், is usually the error. Third, does the written form look pronounceable in normal speech? Sandhi exists to make speech flow, and a form that creates a consonant cluster speakers avoid is suspect. During revision she should not simply record the answer: she should record which rule applied and which source was wrong, so the error is diagnostic. If two sources still conflict after all three checks, she should flag it to her teacher rather than memorise either form.