presentable category and ind

1. Proposition

2. Proof

2.1. 1) 20241204-presentable_category_and_ind_5667b5be7592236ab833642a1d2a85ce8a5490a6.svg 2)

special case

2.2. 2) 20241204-presentable_category_and_ind_5667b5be7592236ab833642a1d2a85ce8a5490a6.svg 3)

see:

where the kappa filtered colimits exist by assumption

2.3. 3) 20241204-presentable_category_and_ind_5667b5be7592236ab833642a1d2a85ce8a5490a6.svg 1)

2.3.2. object as colimit of 20241204-presentable_category_and_ind_dc8fc442dddded85f3f5ead0ba0954d560bc5651.svg

Let 20241204-presentable_category_and_ind_de2bd6f20268d85d9327de72f69f5a18efe48b8c.svg be the smallest full infinity subcategory containing 20241204-presentable_category_and_ind_dc8fc442dddded85f3f5ead0ba0954d560bc5651.svg and 20241204-presentable_category_and_ind_d09a997b979e82e7400788faa006c0d121254cf8.svg-small colimits of 20241204-presentable_category_and_ind_dc8fc442dddded85f3f5ead0ba0954d560bc5651.svg. Then 20241204-presentable_category_and_ind_de2bd6f20268d85d9327de72f69f5a18efe48b8c.svg is small, as we have an epi on objects given by the functor

20241204-presentable_category_and_ind_0f7c2b739100a28f31714ec07318ab943f2b8402.svg

We want to show that 20241204-presentable_category_and_ind_5cb381d2a73e2555d8509c7c2f6fa696f0946e09.svg

There exists a factorization

20241204-presentable_category_and_ind_9b12deedbe30426c3ec437d1b53150b5e7dbe0a6.svg

since 20241204-presentable_category_and_ind_bcd5f9647c25cd53e1c4bddec74e23564210ef34.svg is cocomplete (cf. universal property of the presheaf category)

Then 20241204-presentable_category_and_ind_b8e0978eeeaada0c505f6c5ee1958bf16239b119.svg is a left adjoint with right adjoint given by restriction 20241204-presentable_category_and_ind_893f606bd9a7f5ac644f1000617a0984bd344418.svg, i.e.

20241204-presentable_category_and_ind_e54f1d2ba57259e447fda8d03e25ce8bbf18e6eb.svg
20241204-presentable_category_and_ind_6f4b65e83689e473bfb90ae3b12cb46b233eb546.svg

Here 20241204-presentable_category_and_ind_e71b6e241e2d136c0afa32867938587dff835b24.svg preserves limits (cf. mapping space functor preserves limits), hence restricts

20241204-presentable_category_and_ind_4967c9da73836752da2c130b3c02edf1de008576.svg

(cf. ind object and preserving filtered limits)

This provides an adjunction

20241204-presentable_category_and_ind_3870a8502134835a4ba40217a334840b5bbdaacf.svg

Then as 20241204-presentable_category_and_ind_de2bd6f20268d85d9327de72f69f5a18efe48b8c.svg consists only of 20241204-presentable_category_and_ind_d09a997b979e82e7400788faa006c0d121254cf8.svg-compact objects (cf. kappa small colimit of kappa compact objects), we may conclude that

20241204-presentable_category_and_ind_170ee502480503d2f9e1f4738ada8ca6cc531213.svg

preserves 20241204-presentable_category_and_ind_d09a997b979e82e7400788faa006c0d121254cf8.svg-filtered colimits.

Then we may proceed similar to accessible category and Ind TODO

Author: anton

Created: 2024-12-09 Mo 11:19