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Decision Year 1
AS Further Maths- Edexcel
Question | Answer |
---|---|
What is an algorithm? | Finite sequence of step-by-step instructions carried out to solve a problem |
What columns should you use for a trace table? | Step no. - Variables - Print |
What does a round box mean in a flow chart? | Start/End |
What does a box mean in a flow chart? | Instruction |
What does a diamond mean in a flow chart? | Decision |
How do you carry out a bubble sort? | Compare adjacent items. If they are in order, leave them. If they are not in order, swap them. The list is in order when a pass is completed without any swaps. |
What do you need to remember at the end of a bubble sort? | Write the order once more- to show no change |
How do you carry out a quick sort? | Select a central piot and split the items into two sub-lists. One sub-list contains items less than the pivot, the other, greater. You then keep selecting pivots until all items are in order. |
What are the 3 bin packing algorithms? | first-fit, first-fit decreasing, full-bin |
How do you calculate the lower bound of a bin-pack? | Sum the data and divide by how much can fit in one bin. Always round UP |
How do you carry out a first-fit bin pack? | Place them in bins in the order they are given as. If an item goes over the max storage, move it to the next bin |
How do you carry out a first-fit decreasing bin pack? | Re-write the list in decreasing order. Then place them in bins in order. If an item goes over the max storage, move it to the next bin |
How do you carry out a full-bin pack? | Combined items so that they max out bins. Remaining items- use first-fit. |
What is the order of the bubble and quick sort? | n² |
How do you work out estimated times using the order of an algorithm? | (new amount of data / old amount of data)^(order index) x (time for old amount) |
What is a node/ vertex? | Point on a graph |
What is an edge/ arc? | Line segment of a graph |
What is a vertex set? | List of vertices |
What is an edge set? | List of edges |
What is a subgraph? | A part of an original graph |
What is the degree/ valency on a vertex? | Number of incident edges |
What is a walk? | Route through the graph along edges from one vertex to the next |
What is a path? | Walk where no vertex is visited more than once |
What is a trail? | Walk in which no edge is visited more than once |
What is a cycle? | A walk in which the end vertex is the same as the start vertex and no other vertex is visited more than once |
What is a Hamiltonian cycle? | A cycle that includes every vertex |
What is a connected graph? | A graph where all nodes are attached by arcs |
What is a loop? | An edge which starts and finishes at the same vertex |
What is a simple graph? | No loops and at most one edge connecting two vertices |
What is a directed graph? | Graph where edges have a direction |
What is the sum of the degrees? | 2 x no. edges |
What is a tree? | A connected graph with no cycles |
What is a spanning tree? | Subgraph which includes all the vertices and is a tree |
What is a complete graph? | Every vertex is directly connected to all other vertices |
What is an isomorphic graph? | Graphs which display the same information, just are drawn differently |
What is an adjacency matrix? | Describes the number of arcs connecting each pair of vertices. (Vertices written along the side and top) |
What is a distance matrix? | Matrix which describes the weight of each arc (Vertices written along the side and top) |
What are the two algorithms used to calculate minimum spanning trees? | Kruskals and Prims |
What is Kruskal's algorithm? | Sort all arcs into ascending order of weight. Select smallest to start the tree. Consider the next in the list, add it if it doesn't form a cycle. Repeat until all nodes are connected |
What is Prim's algorithm (on a graph) ? | Choose any vertex. Select the smallest arc it is incident to, add it to the tree. Keep selecting the smallest possible arc (assuming it doesn't form a cycle). |
What is Prim's algorithm (on a distance matrix) ? | Choose any vertex. Delete the row. Number the column of the vertex. Put a ring around the lowest undeleted entry. Delete the row. Number the column of the vertex ............ |
What is Dijkstra's algorithm used for? | Finding the shortest path from S to T through a network |
What is Dijkstra's algorithm? | Label the start S with the final label 0. Record a working value at every node that S connects to. (Replace working value if a smaller one is found). Select the smallest working value, this is now the final value. Work out all the working values... |
How do you work out the shortest path after completing Dijkstra's algorithm? | Work backwards, arc is part of it if the working value-weight = working value of previous node |
What is an eulerian graph? | A connected graph where all vertices have even valency |
What is a semi-eulerian graph? | A connected graph where only two vertices have odd valency |
What is the shortest route of an eulerian graph? | The total weight of the graph |
What is the shortest route of an semi-eulerian graph? | The total weight of the graph + shortest path between odd vertices |
What is the route inspection algorithm? | 1 identify odd vertices 2 consider all pairing 3 select smalled weight pairing 4 add a repeat of that pairing |
What three things do you need to give to formulate a linear programming problem? | 1) Decision variable (x,y,z) 2) The objective, maximise/ minimise 3) The constraints (all inequalities) |
What constraints won't be given in the question? | Greater-than or equal to zero constraints |
What is the name for the region which satisfies the constraints? | Feasible region |
How do you optimise an equation using the graphical method? | Align a ruler with the objective line and move it along the graph, the last point it touches = max, first = min |
How do you optimise an equation using the vertex method? | Work out the co-ordinates of every vertex and plug those values into the objective. |
What is the difference when a linear programming question asks for an integer solution? | Consider the integer points surrounding the optimal vertex. |
What is a precedence table? | Table which shows which activities must be completed for others to start |
What do arcs represent on a network (critical path analysis) ? | Activites |
What do vertices represent on a network (critical path analysis) ? | Completion of those activities (events) |
What are the names for the first and last nodes (critical path analysis) ? | Source and sink node |
What is a dummy activity? | Shows dependecies between activites (no time or cost) |
How many activities go between 2 event? | 1 only |
How do you work out early event times? | Forward pass. (top box) Greatest value of all (total ) values entering the box |
How do you work out late event times? | Backward pass. (bottom box) Smallest value of all (total) values leaving the box |
How can you tell in an activity is critical? | The events on either side have equal late and early times and the largest event time - smallest = weight of activity arc |
What is a critical path? | Path from source to sink containing only critical activities |
How do you calculate total float? | latest finish time - duration - earliest start time |
What is the float of a critical activity? | 0 |
What is a Gantt (cascade) chart? | Graph which displays each activities earliest start time, earliest finish time and float |