A construction of infinite sets of intertwines for pairs of matroids

An intertwine of a pair of matroids is a matroid such that it, but none of its proper minors, has minors that are isomorphic to each matroid in the pair. For pairs for which neither matroid can be obtained, up to isomorphism, from the other by taking free extensions, free coextensions, and minors, we construct a family of rank-k intertwines for each sufficiently large integer k. We also treat some properties of these intertwines.Comment: 11 page

Transversal Lattices

A flat of a matroid is cyclic if it is a union of circuits; such flats form a lattice under inclusion and, up to isomorphism, all lattices can be obtained this way. A lattice is a Tr-lattice if all matroids whose lattices of cyclic flats are isomorphic to it are transversal. We investigate some sufficient conditions for a lattice to be a Tr-lattice; a corollary is that distributive lattices of dimension at most two are Tr-lattices. We give a necessary condition: each element in a Tr-lattice has at most two covers. We also give constructions that produce new Tr-lattices from known Tr-lattices.Comment: 12 pages; 5 figure

An integrated circuit switch

Multi-chip integrated circuit switch consists of a GaAs photon-emitting diode in close proximity with S1 phototransistor. A high current gain is obtained when the transistor has a high forward common-emitter current gain

Lattice path matroids: the excluded minors

A lattice path matroid is a transversal matroid for which some collection of incomparable intervals in some linear order on the ground set is a presentation. We characterize the minor-closed class of lattice path matroids by its excluded minors.Comment: 13 pages, 2 figure

Photon-coupled isolation switch Quarterly report, 1 Jan. - 31 Mar. 1967

Design, development, and testing of new integrated circuit switch devic

Photon-coupled isolation switch Quarterly report, 1 Oct. - 31 Dec. 1966

Integrated circuit photon coupled isolation switc

Photon-coupled isolation switch Quarterly report, 1 Jul. - 30 Sep. 1966

Integrated circuit isolation switch using photon couplin