Hindi infinitives can inflect for gender.

For instance, the infinitive करना has forms such as करना, करनी, करने, etc. which parallel the forms of marked nouns/adjectives.

Infinitives inflect according to gender in certain circumstances, such as the following:

• When they complement a verb in ergative alignment.
• When they are part of a compulsion idiom
• When they are in the passive voice

Infinitives inflect according to case in many situations. This note is about their inflection according to gender.

Complementary Infinitives and Ergative Alignment

Here are a few general principles about complementary infinitives used with verbs in ergative constructions (i.e. with ने):

1. Infinitives that complement verbs in ergative alignment (e.g. लिखनी in “मैंने किताब लिखनी शुरू की”) may inflect according to the gender of their object, or the invariable masculine singular may be used (e.g. “मैंने किताब लिखना शुरू किया”). You can think of the infinitive as the verb’s “object”, so लिखना entails किया, etc. The inflected infinitive is more common. If the verb is not in ergative alignment, then the invariable masculine singular form is used (e.g. “मैं किताब लिखना शुरू करूंगा”).
2. If a complementary infinitive is inflected for gender, it inflects according to the number of its object too (e.g. उसने केले खाने शुरू कर दिए)
3. The main verb may or may not be nasalized; there is no strict rule here. Some speakers prefer one way, some another. Fortunately, the difference in pronunciation (nasalization) and writing (bindu) is pretty subtle anyway, so most people won’t even notice. Here are some general principles:
   1. Only the last word is nasalized (e.g. “शुरू कर दी हैं” and not “दीं हैं”).
   2. If होना is the final word, it’s generally nasalized/pluralized if the object is plural (e.g. “उसने अपनी यात्रा की तैयारियां करनी शुरू कर दी हैं”)
   3. With other verbs, the last verb may or may not be nasalized (although it is always matches the object in number) (e.g. “उसने केले खाने शुरू कर दिए”, “मैंने दो किताबें लिखनी शुरू कीं”, etc.).

To state the rules in #3 another way: the main verb matches the infinitive, but it may or may not be nasalized.

These principles are very likely to be broken! I’ve read and heard such sentences many different ways. I’ve asked native speakers and they say that they cannot clearly discern which way is preferable.

The good news: since there is so much variability, it’s not likely that you’ll make a mistake if you guess. Native speakers probably don’t know what is “right” in many situations too. With enough experience, this will probably become intuitive.

I like to think of this as a “cascade”: picture a waterfall with water trickling down from one rock to another. The gender “cascades” from the object to the infinitive to the main verb.

If the object of the infinitive is “blocked” by a postposition, then the infinitive does not inflect for gender. Thus, infinitives obey rules that are similar to the rules that verbs obey.

Infinitives in Compulsion Idioms

The rules for ergative constructions are very similar to the rules for compulsion idioms. In compulsion idioms, the infinitive inflects according to gender and number.

In one of the transcripts (Sarabhai vs. Sarabhai Ep. 28 ), there is an instance of this phenomenon: “बाद में घोड़ा लुढ़क गया और फिर गाड़ी चलानी बंद करनी पड़ी”. Recall that the same rules apply to “compulsion idioms” that apply to ergative constructions.

Here are a few variations of a sentence:

हमें अपनी समस्याओं का हल करना पड़ेगा
हमें अपनी समस्याओं को हल करना पड़ेगा
हमें अपनी समस्याएँ हल करनी पड़ेंगी

Infinitives in the Passive Voice

In the passive voice, infinitives often inflect according to their subject. In the active voice, the “subject” of infinitives is generally marked with का as in मेरे जाने के बाद, and so such infinitives are inflected according to case and not gender.

बड़े और लंबे समय के प्रयोग किए जाने ज़रूरी हैं – “It’s necessary for some large and long-lasting experiments to be performed”