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Commit 2020-09-02 19:38 9d42f6c6

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feat(order/rel_iso): define rel_hom (relation-preserving maps) (#3946) Creates a typeclass for (unidirectionally) relation-preserving maps that are not necessarily injective (In the case of <= relations, this is essentially a bundled monotone map) Proves that these transfer well-foundedness between relations

Estimated changes

deleted def order_iso.osymm
added theorem rel_embedding.ext
added theorem rel_embedding.ext_iff
deleted def rel_embedding.rsymm
added theorem rel_hom.coe_fn_inj
added theorem rel_hom.coe_fn_mk
added theorem rel_hom.coe_fn_to_fun
added theorem rel_hom.comp_apply
added theorem rel_hom.ext
added theorem rel_hom.ext_iff
added theorem rel_hom.id_apply
added theorem rel_hom.map_rel
added def rel_hom.preimage
added structure rel_hom
modified theorem rel_iso.coe_fn_mk
modified theorem rel_iso.ext
added theorem rel_iso.ext_iff
deleted def rel_iso.rsymm