- Meeting 34 : Tue, Mar 19, 12:00 pm-12:50 pm
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Boolean Circuit Model of Computation. The first few questions. Why circuits? Connections to parallel algorithm design. The relevant parameters of the circuit model - Size, depth, fanin.
What is allowed as a gate? Basis and completeness. Post's characterization of a complete basis (statement).
- Meeting 35 : Thu, Mar 21, 11:00 am-11:50 am
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P/poly = functions computed by polynomial sized circuits. The circuit lower-bound problem. Uniformity, Log-space Uniformity. P is computed by uniform polysize circuits. Review of parameters and questions.
- Meeting 36 : Fri, Mar 22, 10:00 am-10:50 am
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Shannon's counting argument. Lupanov's construction.
- Meeting 37 : Sat, Mar 23, 04:30 pm-05:30 pm
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Exercises | |
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Gate Elimination Argument for Circuit Lower Bounds. Lower bounds for Parity and Threshold.
- Meeting 38 : Sat, Mar 23, 05:30 pm-06:30 pm
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Simple functions and their circuits, PARITY, ADD.
- Meeting 39 : Mon, Mar 25, 08:00 am-08:50 am
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The class NC.The class AC-hierarchy. Interleaving with NC hierarchy. Uniform NC^1 is contained in L.
- Meeting 40 : Tue, Mar 26, 10:00 am-10:50 am
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NL is contained in uniform-AC^1. Back to NC^1, Adding n, n-bit numbers. Trivial AC^1 upper bound. Offman's technique and the NC^1 upper bound. Majority in NC^1. Constant depth reductions.
- Meeting 41 : Thu, Mar 28, 11:00 am-11:50 am
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Zooming in to NC^1. Review of constant depth reductions.
Six Problems : ADD(n,n). MULT(2,n), Th(n,k), BCOUNT, MAJ.
NC^1 upper bounds. Constant depth reductions among these problems. Motivation and definition of the class TC^0.
- Meeting 42 : Mon, Apr 01, 08:15 am-08:50 am
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Symmetric Functions are in TC^0. Motivation and definition of the class ACC^0. The hierarchy interleaving with NC and AC hierarchies.
- Meeting 43 : Tue, Apr 02, 12:00 pm-12:50 pm
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Formulas, BF = NC^1. Formula size lower bounds,
- Meeting 44 : Thu, Apr 04, 11:00 am-11:50 am
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Sabbotavskaya's Lower bound using Restrictions. Lower Bounds for Parity.
- Meeting 45 : Fri, Apr 05, 10:00 am-10:50 am
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Nechiporuk's Method. Lower bound for Indirect Access function.
- Meeting 46 : Sat, Apr 06, 08:15 am-09:15 am
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Proof of Nechiporuk's Theorem.
- Meeting 47 : Sat, Apr 06, 09:15 am-10:15 am
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Nechiporuk's "hardness embedding" technique. Extensions of Sabotavskaya's argument to random restrictions. Andreev's Lower Bound. Shrinkage Exponent.
- Meeting 48 : Mon, Apr 08, 12:00 pm-12:50 pm
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Constant depth circuits cannot compute parity in polysize. Overview of the proof. Trivial cases like AND, OR. First nontrivial case - DNF. The switching Lemma. Proof of Switching Lemma.
- Meeting 49 : Tue, Apr 09, 12:00 pm-12:50 pm
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Inductive Argument. Exponential size lower bounds for constant depth circuits computing parity.
- Meeting 50 : Fri, Apr 12, 10:00 am-10:50 am
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Representation of Boolean functions by polynomials. Upper bound on the degree required to agree with a size s depth d ckt on most of the inputs.
- Meeting 51 : Mon, Apr 15, 08:00 am-08:50 am
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If we can represent PARITY using a polynomial of degree t, then we can represent all functions with polynomials of degree (n+t)/2. But there are not that many polynomials whose degree is that small but there are too many Boolean functions. Razborov-Smolensky lower bound for PARITY.
- Meeting 52 : Tue, Apr 16, 12:00 pm-12:50 pm
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Monotone Circuits, Lower Bounds known. Negation Limited circuits - the story so far. Razoborov's lower bound for monotone circuits. Proof strategy.
- Meeting 53 : Thu, Apr 18, 11:00 am-11:50 am
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Clique Approximators. Construction of the approximate circuit. Sunflower Lemma.
- Meeting 54 : Fri, Apr 19, 10:00 am-10:50 am
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Lower bound on the error estimate for the approximate circuit. Upper bound on the error by counting that for each gate. The lower bound argument.
- Meeting 55 : Mon, Apr 22, 08:00 am-08:50 am
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Branching Programs and Skew circuits. From space bounded algorithms to Branching Programs. Width of the Branching Programs.
- Meeting 56 : Tue, Apr 23, 12:00 pm-12:50 pm
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Programs over groups. Permutations. Conjugates, Cycle conjugacy lemma.
- Meeting 57 : Wed, Apr 24, 05:30 pm-06:30 pm
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Barrington's theorem for width-5. Role of Non-solvability of the group.